Mobile communications system and control method thereof

ABSTRACT

Disclosed is a mobile communications system including a plurality of base station apparatuses which are located at geographically dispersed locations and perform a wireless communication with a mobile device. The system further includes a maximum ratio combining unit which performs maximum ratio combining processing regarding a signal the base station apparatuses receive from the mobile device, and a selection combining unit which performs selection combining processing regarding the signal from the mobile device. A selection unit included in the system selects one or both of the maximum ratio combining unit and the selection combining unit according to at least one of an external factor and a change of a distribution state of the mobile device under communication.

INCORPORATION BY REFERENCE

This application is based upon and claims the benefit of priority fromJapanese Patent Application No. 2006-339939, filed on Dec. 18, 2006, thedisclosure of which is incorporated herein in its entirety by reference.

BACKGROUND OF THE INVENTION

1. Technical Field

The present invention relates to a technical field of signal combiningin a mobile communications system.

2. Background Art

In the mobile communications system, a mobile terminal carried by a userand a base station apparatus are connected with each other by acommunication line using a wireless communication medium (i.e. radiowave). The user of the mobile terminal can communicate with others whilemoving. Since the feature is attractive to the user, the mobilecommunications system is becoming widely used.

Generally, an important issue in the mobile communications system is torealize a communication system which uses energy (i.e. electric power)as little as possible when transmitting a signal via a wirelesscommunication medium. In other words, it is a very important issue toreduce a required electric power when establishing a communication linevia a wireless communication medium i.e. wireless communication link.That reason is that interference between a wireless communication linkused by the user and a wireless communication link used by another usercan be reduced by establishing the wireless communication link that usesa minimum electric power. As a result, an increase of a communicationcapacity can be advantageously obtained in a limited communication band.

As one of methods for reducing the required electric power in thewireless communication link, there is the method of improving thereception efficiency in the base station apparatus. An improvement of areception efficiency means that an electric power of a transmission side(i.e. mobile terminal) that is required for obtaining a necessarysignal-to-noise ratio (S/N ratio) can be reduced.

A so-called third generation mobile telecommunications system employs acode division multiple access (CDMA) communication method. A CDMAcommunication system employs a communication form that is different froma conventional access method (for example, frequency division multiplexaccess (FDMA) communication system, time division multiplex access(TDMA) communication system, or the like).

That is, in the CDMA communication system, a plurality of wirelesscommunication links are simultaneously established between the mobileterminal and the base station apparatus. In such communication,generally, an operation called as “soft handover” or “soft handoff” isperformed.

A communication link between the mobile terminal and the base stationapparatus includes “a down link” and “an up link”. The down link is acommunication link for transmitting a wireless signal to the mobileterminal from the base station apparatus. On the other hand, the up linkis a link for transmitting the wireless signal to the base stationapparatus from the mobile terminal.

In a connection mode of the down link in the CDMA communication system,each of a plurality of base station apparatuses transmits a radio wave.One mobile terminal receives radio waves transmitted from the pluralityof base station apparatuses. Since the above mentioned connection modeis used, a so-called RAKE reception method is employed in the CDMAcommunication system.

The mobile terminal employing the RAKE reception method receives signalsfrom a plurality of base station apparatuses and one or more circuitstherein separate received signals individually. The mobile terminalperforms an adjustment so that the signals have the same arrival time,and also weight received signals so as to obtain a maximum receptiongain. After that, the mobile terminal despreads the weighted signal toobtain a decoded baseband signal.

On the other hand, in a connection mode of the up link in the CDMAcommunication system, a radio wave transmitted by one mobile terminal isreceived by a plurality of base station apparatuses which exist aroundthe mobile terminal. In the CDMA communication system, there are severalmethods for processing a wireless signal received by the base stationapparatus with respect to an internal configuration of each base stationapparatus.

In a first method, a plurality of base station apparatuses that arelocated at geographically dispersed locations individually receive asignal transmitted from the mobile terminal and also despread a receivedsignal to obtain the decoded baseband signal. The signal that isindividually decoded in each base station apparatus in the method isselected based on signal quality thereof. The method is called as “softhandoff”. After quality of each of a plurality of received signals inthe process mentioned above is individually evaluated, only a normalsignal is selected and the selected signals are combined to obtain abaseband signal. Such processes are called as “selection combining(SC)”.

A second method is a method using a so-called “sector base station”. Asector base station includes a plurality of antenna elements that iscalled as a sector antenna. A plurality of sector antennas of the sectorbase station individually receive a wireless signal transmitted from themobile terminal and the sector base station adjusts the signal so thateach arrival time of the signal received by the sector antenna becomesequal to each other. After that, the sector base station combinesreceived signals whose arrival times are adjusted to be equal to eachother. The second method is, in principle, the approximately same asRAKE method in a connection mode of the down link mentioned above (thatis, a method in which downlink signals received from a plurality of basestation apparatuses are combined in one mobile terminal). The method iscalled as “softer handoff”. Each of received signals whose arrival timesare adjusted to be equal to each other is weighted so as to maximizereception gain. Such processes is called “maximum ratio combining(MRC)”. Each of received signals which is weighted in the sector basestation is decoded to obtain the baseband signal.

Japanese Patent Application Laid-Open No. 2000-13289 discloses a methodin which a soft handoff (selection combining) and a softer handoff(maximum ratio combining) are combined. In the method, signals receivedby a plurality of sector antennas (sector base stations) which employ aRAKE reception method is decoded to obtain the baseband signal. Thedecoded signal is compared with a signal decoded from the basebandsignal based on a received signal in another base station apparatus. Inthe method, one of the decoded signals that are compared with each otheris selected based on quality of the decoded signals. That is, areception form of the RAKE reception method in the method is a receptionform in which the softer handoff and the soft handoff in which a signalobtained by the softer handoff or a signal obtained by another basestation apparatus is chosen according to quality information arecombined.

A technology of which a wireless signal transmitted from one mobileterminal is received by a plurality of base station apparatuses or aplurality of sector antennas in the up link is called a diversitytechnology. By employing the diversity technology, even if a receptionpower level of a signal received by the base station apparatus of aplurality of base station apparatuses is temporarily reduced due tobuildings or the like, a signal transmitted from the mobile terminal canbe efficiently received by a signal received by another base stationapparatuses. An effect in such diversity technology is called a spacediversity effect.

However, with respect to a reception gain (reception efficiency) of thebase station apparatus, an effect of the selection combining (SC)differs from that of the maximum ratio combining (MRC). Hereinafter, thetwo cases will be compared.

First, a first reception form is a case in which two base stationapparatuses that are located at geographically dispersed locationsreceive a wireless signal, respectively, and perform selection combiningprocessing based on the received wireless signals. A second receptionform is a case in which two sector antennas provided in one sector basestation receive a wireless signal, respectively and maximum ratiocombining processing is performed based on the received wirelesssignals.

When selection combining (SC) processing is performed, it is necessarythat a received power in at least one base station apparatus of aplurality of base station apparatuses meets a predetermined receptionlevel that is required for a reception.

On the other hand, when maximum ratio combining processing (MRC) isperformed, signal combining is performed by adding a plurality ofreceived signals received by each sector antenna in one sector basestation. For this reason, the maximum ratio combining (MRC) has feature,there is no necessity that a level of a signal before a combining thatis received by each sector antenna meets the above predeterminedreception level for the selection combining (SC).

In other words, the above feature means that in the up link, a receptiongain of the maximum ratio combining method is generally higher than thatof the selection combining method. That is, in a maximum ratio combiningmethod, a good quality communication can be realized even if atransmission power of the mobile terminal for satisfying a requiredsignal level is low in comparison with a required transmission power forthe selection combining.

Accordingly, when the maximum ratio combining method is extensivelyused, a transmission power of the mobile terminal can be reduced. As aresult, a capacity of the up link can be increased.

The maximum ratio combining method has an advantage of a high receptiongain. However, when the maximum ratio combining processing (MRC) isperformed, a communication line in the base station side which is usedin order to perform signal combining has to be a high-speed line whichis capable of transferring a signal without reducing a transmission rateof a signal in a wireless section. Since there are such restrictions,the maximum ratio combining method cannot be used for all the connectionpatterns between the mobile terminal and the base station apparatus (ora sector antenna). Here, the above restrictions will be described morespecifically.

In a selection combining method, a signal with a several MHz bandwidthin a high frequency band in a wireless section is decoded, and also thebaseband signal with about ten and several kHz bandwidth obtained by adecoding is produced. In the selection combining method, it is enough totransfer the baseband signal and a signal in which some amount ofquality information is added to a point where a judgment of selectioncombining is performed. That is, in the selection combining method, acommunication line with about ten and several kHz bandwidth is enough totransfer a signal to the point where a judgment of selection combiningis performed.

In contrast, in the maximum ratio combining method, first, each sectorantenna receives a signal with a several MHz bandwidth in the highfrequency band in the wireless section. In the maximum ratio combiningmethod, it is necessary to transfer the signal in the high frequencyband to a point where a maximum ratio combining process is performed,without changing a transmission rate or with keeping the signal to be inan equal bandwidth. This is because, it is necessary to adjust anarrival time of each received signal and weight a reception gain asmentioned above in the maximum ratio combining method. For this reason,in the maximum ratio combining method, a high speed line whose speed isalmost the same as that of the above wireless section is required for acommunication line of a base station side.

Accordingly, for the reason mentioned above, generally, the maximumratio combining method is employed in one base station (sector basestation) which is capable of handling signals individually received by aplurality of antenna elements (sector antennas) with keeping a speed ofthe signal almost the same as a high speed signal in the wirelesssection. That is, the maximum ratio combining method is not employed fora plurality of base station apparatuses that are located atgeographically dispersed locations.

However, in an actual situation, there are few cases in which a mobileterminal is located only in an area which is controlled by one basestation and is overlapped with neighboring sectors (the area is acoverage area of the base station). In fact, a mobile terminal isfrequently located in a coverage area of a plurality of base stationapparatuses which face each other across the mobile terminal. That is,it is considered that it is often the case in which a mobile terminal islocated in a plurality of base station areas that are located atgeographically dispersed locations. Accordingly, in case that a mobileterminal exists in a plurality of base station areas, if a receptiongain can be improved, as a result, a capacity of an up link can beincreased.

Accordingly, it is technically possible to connect between a pluralityof base station apparatuses that are located in geographically dispersedpoints with a high speed line whose transmission speed is almost thesame as that of the wireless section, in order to increase a capacity ofan up link. However, it is impractical to connect between all theneighboring base station apparatuses with the high speed line in a meshwhen cost is taken into consideration.

However, a system configuration in which in an up link which transfers asignal from a mobile terminal to a base station apparatus, the maximumratio combining (MRC) method is employed only between sector antennasthat are adjacently arranged in one base station apparatus (sector basestation) and meanwhile, the selection combining (SC) method is employedbetween different base station apparatuses that are located at otherlocations should be improved from a view point of improving anefficiency of a reception gain of an up link. Here, a present status andan issue of combining processing that is employed in such systemconfiguration will be described more in detail with reference to FIG.45, FIGS. 46A to 46C and FIGS. 47A to 47C.

FIG. 45 is a figure illustrating a system configuration in which variouskinds of base station apparatuses are connected with each other in arelated mobile communications system and a processing procedure of areceived signal.

In FIG. 45, a base station apparatus 12020 is a sector base stationhaving three sector antennas 12011, 12012 and 12013. The base stationapparatus 12020 forms a base station area 121 as a coverage area by thethree sector antennas.

On the other hand, a base station apparatus 12021 is a base stationapparatus having a non-directional antenna (for example,omni-directional antenna etc.) and forms a base station area 122 as acoverage area.

When two base station apparatuses 12020 and 12021 are located atgeographically dispersed locations as shown in FIG. 45, a mobileterminal 101 is located at a point on a boundary between the basestation area 121 and the base station area 122. The mobile terminal 101exists in an overlapped coverage area of two sector antennas 12012 and12013 in the base station area 121, and also exists in a coverage areaof the base station apparatus 12021 (base station area 122). Receivedsignals from the sector antennas 12012 and 12013 are processed inside ofthe one base station apparatus (sector base station) 12020. Since a highspeed line can be used for the received signals from the sector antennasinside the base station apparatus, a signal combining by the maximumratio combining method can be applied.

More specifically, a maximum ratio combiner (CMB) 1301 is installed inthe base station apparatus 12020 whose coverage area is the base stationarea 121. The maximum ratio combiner 1301 performs maximum ratiocombining processing based on received signals from the three sectorantennas (in a case shown in FIG. 45, received signals from the twosector antennas 12012 and 12013). The maximum ratio combiner 1301decodes a baseband signal based on an output of maximum ratio combiningprocessing and also adds predetermined quality information to thedecoded signal. An output signal of the maximum ratio combiner (CMB)1301 is transferred to a diversity handover trunk (DHT) 1302 in order toperform selection combining with a signal from an antenna provided inanother base station apparatus.

On the other hand, in order to perform selection combining with a signalfrom an antenna provided in another base station apparatus, the basestation apparatus 12021 decodes a signal received in the base stationarea 122 into a baseband signal, and also adds predetermined qualityinformation to the decoded signal. An output signal of the base stationapparatus 12021 is transferred to the diversity handover trunk (DHT)1302.

The diversity handover trunk 1302 receives a baseband signal decoded inthe base station apparatus covering the base station area 121 andreceives a baseband signal decoded in the base station apparatuscovering the base station area 122. Moreover, by referring to thequality information that attaches to each received baseband signal, thediversity handover trunk 1302 selects one of two received basebandsignals based on the quality information. The selected signal is sent toa RNC (radio network controller) 1307.

In case of an example shown in FIG. 45, with respect to quality of asignal transmitted from the mobile terminal 101, it is necessary that aquality of either one or both of two signals that are inputted to thediversity handover trunk 1302 has to satisfy a predetermined level.Here, the two signals include a signal obtained by a process in whichsignals received by the sector antennas 12012 and 12013 are processed bya maximum ratio combining and the processed signal is decoded into abaseband signal and a signal obtained by a process in which a signalreceived by the base station apparatus 12021 is decoded into a basebandsignal.

However, a higher reception gain can be obtained by combining all thesignals received by the sector antennas 12012 and 12013 and the basestation apparatus 12021 by using the maximum ratio combining method. Areason why such method can not be actually applied is that a high speedline which can perform maximum ratio combining processing in an externalapparatus for a plurality of base station apparatuses which areinstalled at geographically dispersed locations is not available.

That is, in an up link, in order to perform maximum ratio combining(MRC) processing based on outputs from receiving antennas as many aspossible (output signal of a base station apparatus), it is desirable toprepare all the high speed lines in advance by considering allconnection patterns that are configured between a mobile terminal and abase station apparatus or a sector antenna according to a location of amobile terminal that exists in a service area.

In this case, a base station apparatus having a non-directional antennaor a base station having a sector antenna (hereinafter, it isabbreviated as “base station apparatus group”) to be connected by a highspeed line forms a connection pattern of which a plurality of coverageareas formed by the base station apparatus group are neighboring. Asanother connection pattern, in the base station apparatus group whichshould be connected by a high speed line, one or more base stationapparatus groups exist between neighboring coverage areas and as aresult, a connection pattern is a pattern of which all the coverageareas are close.

However, when a connection pattern of the base station apparatus groupis selected according to the above judgment criteria, even when it isvisually judged that both coverage areas are neighboring or close,actually, there is a case that it is not effective to perform maximumratio combining processing caused by an influence of a position or aheight of a structure which can be an obstacle to a radio wave.

Accordingly, it is not cost-effective to prepare an expensive high speedline in advance by considering all the connection patterns. Moreover, ifthese high speed lines are permanently established, communication linesare wastefully left almost unused. Accordingly, it is required toestablish only a high speed line truly required.

Generally, an area where a mobile communications system is largely usedis a congested urban area or a densely populated area. However, in theareas, a distribution condition of users of a mobile terminal changes atevery moment. For example, since users move for their reasons accordingto some conditions such as in a weekday morning, in a daytime, in anevening, late at night, a weekend or a special event, a distributioncondition of a plurality of mobile terminals changes according to themovement of users. For this reason, it is necessary to reduce aninterference power of an up link by realizing a reception using themaximum ratio combining method among base station apparatuses having thenon-directional antenna and base stations having the sector antenna asmany as possible according to a movement or distribution conditions ofusers (mobile terminals).

Here, in the mobile communications system shown in FIG. 45, a transitionof a connection state of a communication line when a mobile terminalmoves will be described with reference to FIGS. 46A to 46C and FIGS. 47Ato 47C.

FIGS. 46A to 46C are figures generally illustrating a connection mode ofa maximum ratio combiner and a selection combiner in a mobilecommunications system shown in FIG. 45. Further, in FIGS. 46A to 46C,the maximum ratio combiner (CMB) 1301 shown in FIG. 45 is represented asa maximum ratio combining point (MRC-P) 1305. The diversity handovertrunk (DHT) 1302 shown in FIG. 45 is represented as a selectioncombining point (SC-P) 1306.

FIG. 46A shows a situation in which the mobile terminal 101 approachessector antennas 12012 and 12013 and also approaches the base stationapparatus 12021. In such a case, the maximum ratio combining point 1305provided in the sector base station 12020 performs maximum ratiocombining processing to signals received by the sector antennas 12012and 12013. The selection combining point 1306 performs selectioncombining processing based on a signal combined by the maximum ratiocombining point 1305 and a signal received by the base station apparatus(base station apparatus having a non-directional antenna) 12021.

Next, FIG. 46B shows a situation in which the mobile terminal 101 movesto another position that is different from the position shown in FIG.46A. That is, in FIG. 46B, the mobile terminal 101 slightly moves awayfrom the coverage areas by base station apparatus 12021 compared withthe position shown in FIG. 46A and it is located on a boundary betweencoverage areas by sector antennas 12012 and 12013. In this case, it iseffective to apply maximum ratio combining processing to the signalsreceived by the sector antennas 12012 and 12013 in the maximum ratiocombining point 1305. However, in the situation, it is not effective toperform selection combining processing using an output signal of themaximum ratio combining point 1305 and an output signal of the basestation apparatus 12021. Thus, in the situation shown in FIG. 46B, anoutput signal of the base station apparatus 12021 is excluded from aninput source for a signal combining.

FIG. 46C shows a situation in which the mobile terminal 101 moves toanother position that is different from the position shown in FIG. 46Aand FIG. 46B mentioned above. FIG. 46C shows the situation in which themobile terminal 101 is located on a boundary of the base station area122 of the base station apparatus 12021 and on a boundary of the sectorantenna 12013 (base station area 121), further, it is located on aposition which is away from the sector antenna 12012. Then, theselection combining point 1306 performs selection combining processingbased on an output signal of the sector antenna 12013 and a signalreceived by the base station apparatus 12021.

Hereinafter, a difference in signal processing for respective situationsthat are shown in FIGS. 46A to 46C mentioned above will be describedwith reference to FIGS. 47A to 47C.

FIGS. 47A to 47C are figures logically illustrating a relation of acommunication connection of base station apparatuses 12020 and 12021,the maximum ratio combining point 1305 and the selection combining point1306 in the situation shown in FIGS. 46A to 46C.

FIG. 47A is a figure logically showing a connection situation shown inFIG. 46A mentioned above. In FIG. 47A, a bold line connecting the sectorantennas 12012, 12013 and the maximum ratio combining point 1305represents a high speed line which can transfer a signal for performingmaximum ratio combining processing. That is, a high speed line is usedfor a communication line which connects each sector antenna and themaximum ratio combining point 1305 in the sector base station 12020.

Here, the high speed line (i.e. the bold line in FIG. 47A) provided inthe sector base station 12020 is a line which has almost the sameperformance as a transmission link which is capable of transmitting asignal with a several MHz bandwidth in a high frequency band in awireless section as mentioned in a description of the maximum ratiocombining method.

The maximum ratio combining point 1305 performs maximum ratio combiningprocessing based on a signal received by the sector antennas 12012 and12013 and also transfers a signal that represents a result of theprocessing to the selection combining point 1306. The selectioncombining point 1306 performs selection combining processing based on asignal received from the maximum ratio combining point 1305 and a signalreceived from the base station apparatus 12021. Since it is aprecondition that a low speed line is used for each communication linewhich transfers a signal used for selection combining, the communicationline is indicated by a thin line.

Here, a low speed line indicated by a thin line is a line whosetransmission speed is very low compared with that of a high speed linewith a several MHz bandwidth as mentioned above in a description of theselection combining method.

FIG. 47B is a figure logically illustrating a connection situation shownin FIG. 46B mentioned above. In this case, since maximum ratio combiningprocessing is performed by using a signal received from the sectorantennas 12012, 12013, a line connecting the sector antenna and themaximum ratio combining point 1305 is expressed by the same bold line asFIG. 47A. However, a signal received by the base station apparatus 12021is excluded from an input source due to a positional relation of themobile terminal 101 shown in FIG. 46. Thus, a communication line (lowspeed line) between the maximum ratio combining point 1305 and theselection combining point 1306 is not established. That is, theselection combining point 1306 does not perform selection combiningprocessing.

FIG. 47C is a figure logically illustrating a connection situation shownin FIG. 46C mentioned above. Only a signal received by the sectorantenna 12013 is used in the sector base station 12020 due to apositional relation of the mobile terminal 101 shown in FIG. 46C. Then,a low speed line which connects the sector antenna 12013 and theselection combining point 1306 and the low speed line which connects thebase station apparatus 12021 and the selection combining point 1306 areestablished. The selection combining point 1306 performs selectioncombining processing based on signals received via the low speed lines.

In FIGS. 47A to 47C, a high speed line (bold line) which transfers asignal used for maximum ratio combining processing and the low speedline (thin line) which transfers a signal used for selection combiningare selectively established to each sector antenna appropriatelyaccording to a positional relation of the mobile terminal 101. On theother hand, with respect to the base station apparatus 12021 having onenon-directional antenna, only the low speed line (thin line) whichtransfers a signal used for selection combining is established.

As an example mentioned above, it is necessary to transfer a signalreceived in each antenna element to a maximum ratio combining point(maximum ratio combiner) via the high speed line whose transmissionspeed is almost the same as that of a wireless section to performmaximum ratio combining processing. For this reason, in a general systemconfiguration, maximum ratio combining processing is performed only in asector base station in which the high speed line is available. In thiscase, maximum ratio combining processing is performed only between aplurality of sector antennas accommodated in one sector base station.That is, in a conventional mobile communications system, maximum ratiocombining processing cannot be performed between a plurality of basestation apparatuses which are located at geographically dispersedlocations.

SUMMARY

The present invention is made to solve the foregoing and other exemplaryproblems, drawbacks, and disadvantages. A first exemplary feature of thepresent invention is to provide a mobile communications system and acontrol method thereof in which a capacity increase of a communicationline is realized by reducing a power transmitted from a mobile terminalto a base station apparatus based on an improvement of a reception gainof a wireless signal sent to the base station apparatus from the mobileterminal.

According to a first exemplary aspect of the present invention, there isprovided with including

(1) a plurality of base station apparatuses which are located atgeographically dispersed locations and perform a wireless communicationwith a mobile device,

(2) a maximum ratio combining unit which is connectable with theplurality of base station apparatuses for a communication via a firstcommunication line and performs maximum ratio combining processing basedon information corresponding to a received signal from the mobile devicewhich is transmitted from the plurality of base station apparatuses,

(3) a selection combining unit which is connectable with the pluralityof base station apparatuses for a communication via a secondcommunication line and performs selection combining processing based oninformation corresponding to a received signal from the mobile devicewhich is transmitted from the plurality of base station apparatuses and

(4) a selection unit which selects one or both of the maximum ratiocombining unit and the selection combining unit according to at leastone of an external factor and a change of a distribution state of amobile device under communication that exists in a coverage area of theplurality of base station apparatuses with which the mobile deviceperforms a wireless communication, when signal combining is performedbased on the information corresponding to the received signal from themobile device which is transmitted from the plurality of base stationapparatuses, in response to reception of a wireless signal by theplurality of base station apparatuses which is transmitted from onemobile device.

According to a second exemplary aspect of the present invention, thereis provided with including steps of

(1) connecting the plurality of base station apparatuses which arelocated at geographically dispersed locations and perform a wirelesscommunication with the mobile device with the maximum ratio combiningunit that performs maximum ratio combining processing via the firstcommunication line based on information corresponding to a receivedsignal from the mobile device which is transmitted from the plurality ofbase station apparatuses, and also connecting the plurality of basestation apparatuses with the selection combining unit that performsselection combining processing based on the information via the secondcommunication line, and(2) selecting at least one of the maximum ratio combining unit or theselection combining unit according to at least one of an external factoror a change of a distribution state of the mobile device undercommunication that exists in a coverage area of the plurality of basestation apparatuses with which the mobile device performs a wirelesscommunication when performing signal combining based on the informationcorresponding to the received signal from the mobile device which istransmitted from the plurality of base station apparatuses in responseto a reception of a wireless signal transmitted from one mobile devicein the plurality of base station apparatuses.

According to other exemplary aspect of the present invention, there isprovided with including the base station apparatus which performs awireless communication with the mobile device, the base stationapparatus including,

(1) a communication control module which transmits information byestablishing a communication link with at least one of the firstcommunication line used for a communication with the maximum ratiocombining unit that performs maximum ratio combining processing and thesecond communication line used for a communication with the selectioncombining unit that performs selection combining processing based oninformation corresponding to a received signal from the mobile device,(2) a request module which requests an external apparatus to change adestination of the information corresponding to the received signal fromthe mobile device to either the maximum ratio combining unit or theselection combining unit according to a change of a distribution stateof the mobile device under communication.

According to a second exemplary aspect of the present invention, thereis provided with a computer program for controlling an operation of thebase station apparatus which performs a wireless communication with themobile device, the computer program including functions of as follows:

a communication control function which transmits information byestablishing a communication link with at least one of the firstcommunication line used for a communication with the maximum ratiocombining unit that performs maximum ratio combining processing and thesecond communication line used for a communication with the selectioncombining unit that performs selection combining processing based oninformation corresponding to a received signal from the mobile device;and

a request function which requests an external apparatus to change adestination of the information corresponding to the received signal fromsaid mobile device to either the maximum ratio combining unit or theselection combining unit according to a change of a distribution stateof the mobile device under communication.

Further, a first exemplary feature mentioned above is also achieved by acontrol method corresponding to a mobile communications system havingeach configuration mentioned above.

The first exemplary feature mentioned above is also achieved by a basestation apparatus included in mobile communications system mentionedabove.

Moreover, the first exemplary feature mentioned above is also achievedby a computer program for forcing a computer to realize a base stationapparatus mentioned above and a computer-readable storage medium inwhich the computer program is stored.

Other exemplary features and advantages of the present invention will beapparent from the following description taken in conjunction with theaccompanying drawings, in which like reference characters designate thesame or similar parts throughout the figures thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

Exemplary features and advantages of the present invention will becomeapparent from the following detailed description when taken with theaccompanying drawings in which:

FIG. 1 is a figure exemplarily illustrating the entire configuration ofa mobile communications system according to an exemplary embodiment ofthe present invention;

FIG. 2 is a figure exemplifying a relation between a base station areaand a sector antenna in a general mobile communications system;

FIG. 3 is a figure illustrating a state in which a plurality of mobileterminals that are connected with a part of base station apparatuses areconnected by the maximum ratio combining (MRC) in the mobilecommunications system exemplarily illustrated in FIG. 1 and FIG. 2;

FIG. 4 is a figure exemplarily illustrating a situation in which amaximum ratio combining point and a selection combining point areaccommodated together in a physical apparatus in the mobilecommunications system according to an exemplary embodiment of thepresent invention;

FIG. 5 is a figure exemplarily illustrating a connection state of themobile terminal and the base station apparatus in the mobilecommunications system according to an exemplary embodiment of thepresent invention;

FIG. 6 is a figure exemplifying a connection situation of acommunication link between the base station apparatus and the mobileterminal assumed in the mobile communications system according to anexemplary embodiment of the present invention;

FIG. 7 is a figure (table) illustrating a connection situation of acommunication link between the base station apparatus and the mobileterminal shown in FIG. 6;

FIG. 8 is a configuration diagram showing a connection situation of acommunication link between the base station apparatus and the mobileterminal exemplarily shown in FIGS. 6 and 7 from a view point of anetwork connection of the mobile communications system;

FIG. 9 is a figure illustrating a signal transmission route among themobile terminal, the base station apparatus and the maximum ratiocombining point in the situation shown in FIGS. 6 to 8;

FIG. 10 is a figure exemplifying a format of a data packet when eachbase station apparatus shown in FIG. 6 and FIG. 8 transmits to a networka signal received from the mobile terminal;

FIG. 11 is a figure illustrating the situation in which a signalreceived by each base station apparatus is taken in the specific maximumratio combining point 3053 with respect to a connection relationshipamong the mobile terminal, the base station apparatus and the maximumratio combining point shown in FIG. 6, FIG. 8 and FIG. 9;

FIG. 12 is a block diagram showing an internal configuration of themaximum ratio combining point 3051 among three maximum ratio combiningpoints shown in FIG. 11;

FIG. 13 is a figure illustrating a situation in which a signal receivedby each base station apparatus is taken in the specific maximum ratiocombining points 3051 and 3052 with respect to a connection relationshipamong the mobile terminal, the base station apparatus and the maximumratio combining point shown in FIG. 6, FIG. 8 and FIG. 9;

FIG. 14 is a figure illustrating a situation in which signals receivedby the base station apparatuses 2031 and 2041 are taken in by thespecific maximum ratio combining points 3051 and then an output of themaximum ratio combining point and a signal received by the base stationapparatus 2021 are taken in by the specific selection combining point3061 with respect to a connection relationship among the mobileterminal, the base station apparatus and the maximum ratio combiningpoint shown in FIG. 4, FIG. 6 and FIG. 9;

FIG. 15 is a figure showing a signal destination in a connectionsituation shown in FIG. 14;

FIG. 16 is a figure showing a format of a data packet for sending asignal of the mobile terminal to the maximum ratio combining point and aselection combining point via the base station apparatus;

FIG. 17 is a figure showing a situation in which the data packet 5121which should be transferred to the selection combining point 3061 andthe data packet 5021 which should be transferred to the maximum ratiocombining point 3051 are transmitted from the base station apparatus2021;

FIG. 18 is a figure showing a situation until the data packet 5021 istaken in the maximum ratio combining point 3051 from the situation shownin FIG. 17;

FIG. 19 is a figure showing a situation until a use of the selectioncombining point is stopped from the situation shown in FIG. 18;

FIG. 20 is a figure showing a situation in which maximum ratio combiningprocessing is performed based on a signal of the mobile terminal 1012that is received by the base station apparatuses 2041 and 2051;

FIG. 21 is a figure showing a situation in which the base stationapparatuses 2041 and 2051 produce data packets 5041 and 5051 whichshould be transferred to the maximum ratio combining point 3052 and datapackets 5141 and 5151 which should be transferred to a selectioncombining point 3062;

FIG. 22 is a figure showing a situation until a use of the maximum ratiocombining point is stopped from the situation shown in FIG. 20;

FIG. 23 is a figure showing a distribution of the mobile terminal undercommunication at a certain time (t1);

FIG. 24 is a figure showing a distribution of the mobile terminal undercommunication at a different time (t2);

FIG. 25 is a block diagram exemplarily illustrating an internalconfiguration of the base station apparatus according to the exemplaryembodiment;

FIG. 26 is a figure illustrating a change determination method of signalcombining processing;

FIG. 27 is a flowchart of change request processing in which an up-linkelectric power amount is used as an evaluation value;

FIG. 28 is a flowchart of change request processing in which aninformation rate of an up link is used as an evaluation value;

FIG. 29 is a flowchart of change request processing in which the numberof mobile terminals is used as an evaluation value;

FIG. 30 is a system block diagram of an exemplary mobile communicationssystem in a first example;

FIG. 31 is a figure showing a flow of a change operation in a firstexample;

FIG. 32 is a figure showing an example of a switch layout of a consolepanel in a first example;

FIG. 33 is a figure illustrating an operation method of anindication-and-operation switch provided on a console panel in a firstexample;

FIG. 34 is a figure illustrating a management table used for amanagement of an evaluation state and a setting state of a plurality ofbase station apparatuses which are management targets;

FIG. 35 is a system block diagram of an exemplary mobile communicationssystem in a second example;

FIG. 36 is a figure showing a flow of information transmitted andreceived between a central apparatus and a base station apparatus in asequential change method according to a second example;

FIG. 37 is a figure illustrating a management table used for amanagement of an evaluation state and a setting state of a plurality ofbase station apparatuses which are management targets;

FIG. 38 is a flowchart of change control processing using a sequentialchange method that is performed by a central apparatus in a secondexample;

FIG. 39 is a figure showing a flow of information transmitted andreceived between a central apparatus and a base station apparatus in abatch change method according to a second example;

FIG. 40 is a flowchart of change control processing using a batch changemethod that is performed by a central apparatus in a second example;

FIG. 41 is a figure illustrating a management table used for amanagement of an evaluation state and a setting state of a plurality ofbase station apparatuses that are management targets;

FIG. 42 is a figure illustrating a management table that is self-managedby a base station apparatus in a third example;

FIG. 43 is a figure illustrating a configuration of a mobilecommunications system in a third example;

FIG. 44 is a figure showing a flow of information transmitted andreceived between a line connection controller and the base stationapparatus in a third example;

FIG. 45 is a figure exemplarily illustrating a situation in whichvarious types of base station apparatus are connected in a relatedmobile communications system and also illustrating a processingprocedure of a received signal;

FIGS. 46A to 46C are figures generally illustrating a connection mode ofa maximum ratio combiner and a selection combiner in a mobilecommunications system shown in FIG. 45; and

FIGS. 47A to 47C are figures logically illustrating a relation of acommunication connection among the base station apparatus 12020 and12021, the maximum ratio combining point 1305 and the selectioncombining point 1306 in the situation shown in FIGS. 46A to 46C.

EXEMPLARY EMBODIMENT

Exemplary embodiments of the present invention will now be described indetail in accordance with the accompanying drawings.

In the following description, first, an overall operation of a mobilecommunications system according to the exemplary embodiment is describedwith reference to mainly FIGS. 1 to 24. An operation of each apparatusconfiguring the system that realizes the operation specifically and aprocessing configuration are described with reference to FIGS. 25 to 44.

<Overall Operation of a Mobile Communications System>

FIG. 1 is a figure exemplarily illustrating an entire configuration of amobile communications system according to an exemplary embodiment of thepresent invention.

A mobile communications system shown in FIG. 1 mainly includes basestation apparatuses 2011, 2021 and 2031, a maximum ratio combining point(MRC-P) 305, a selection combining point (SC-P) 306, a radio networkcontroller (RNC) 307, a high speed line 1001 and a low speed line 1002.

More specifically, the base station apparatuses 2011, 2021 and 2031perform a wireless communication with a mobile terminal (not shown)which exists in a coverage area (i.e. base station area). Moreover, thebase station apparatus 2011, 2021 and 2031 transmit a signal receivedfrom the mobile terminal as digital data by using the high speed line1001 or the low speed line 1002. An internal configuration of these basestation apparatuses is described later with reference to FIG. 25.

The maximum ratio combining point (i.e. maximum ratio combining unit)305 performs maximum ratio combining processing (MRC) to signalsreceived by the base station apparatuses 2011, 2021 and 2031. An outputof the maximum ratio combining point 305 is transmitted to the selectioncombining point 306. In the exemplary embodiment, the maximum ratiocombining point 305 is located at a location that is geographicallydifferent from locations where the base station apparatuses 2011, 2021and 2031 are arranged.

The selection combining point (i.e. the selection combining unit) 306includes a selection combiner which performs selection combiningprocessing (SC) to signals received by the base station apparatuses2011, 2021 and 2031 and is arranged at a location that is geographicallydifferent from a location where these base station apparatuses arearranged. An output of the selection combining point 306 is transmittedto a radio network controller 307.

The radio network controller 307 controls an operation of the basestation apparatuses 2011, 2021 and 2031 based on an output signal of themaximum ratio combining point 305 or an output signal of the selectioncombining point 306. Further, the radio network controller 307 isconnected to a Mobile service switching center (MSC) (not shown) that isa higher level apparatus.

The high speed line (i.e. a first communication line) 1001 is abroadband communication line which connects the base station apparatuses2011, 2021 and 2031 to the maximum ratio combining point 305 so as toenable a communication with each other. The high speed line 1001 isrepresented by a bold line in FIG. 1. In the exemplary embodiment, thehigh speed line 1001 that is a broadband communication line is mainlyutilized for a maximum ratio combining processing (MRC) (it will bedescribed in detail later).

The low speed line 1002 (i.e. a second communication line) is a narrowband communication line which connects among the base stationapparatuses 2011, 2021 and 2031, the maximum ratio combining point 305,the selection combining point 306 and the radio network controller 307so as to enable a communication with each other. The low speed line 1002is represented by a thin line in FIG. 1. In the exemplary embodiment,the low speed line 1002 that is a narrow band communication line ismainly utilized for selection combining processing (SC) (it will bedescribed in detail later).

Further, in a description mentioned below, an establishment of acommunication line using the high speed line 1001 may be called “MRCconnection”. On the other hand, an establishment of a communication lineusing the low speed line 1002 may be called “SC connection”.

In the exemplary embodiment, a packet link which includes an addressheader representing a transfer destination address, for example, such asan Internet Protocol (IP) network, can be used for the high speed line1001 and the low speed line 1002. Alternatively, a Synchronous DigitalHierarchy (SDH) in which a different time slot is assigned for eachtransfer destination point may be used for the high speed line 1001 andthe low speed line 1002.

The logically equal connection mode may be used for the high speed line1001 and the low speed line 1002. Moreover, in an example shown in FIG.1, the low speed line 1002 is used for a connection between the maximumratio combining point 305 and the selection combining point 306.However, a connection mode using the high speed line 1001 may be usedfor a connection between the maximum ratio combining point 305 and theselection combining point 306.

FIG. 2 is a figure exemplifying a relation between a base station areaand a sector antenna in a general mobile communications system.

In an example shown in FIG. 2, the respective base station areas 21 to24 are formed by four sector base stations which are located atphysically different locations as a coverage area of the sector basestations. The base station areas (21 to 24) of the sector base stationsforms one cell which includes three sectors as shown in FIG. 2 andbelow. That is:

Base station area 21: Sector antennas 2011 to 2013

Base station area 22: Sector antennas 2021 to 2023

Base station area 23: Sector antennas 2031 to 2033 and

Base station area 24: Sector antennas 2041 to 2043

According to an example shown in FIG. 2, which coverage areas of sectorantennas are adjacent to each other or overlapped with each other can beknown.

More specifically, for example, a coverage area of the sector antenna2013 in the base station area 21 is adjacent to coverage areas of thesector antennas 2011 and 2012 in the facing base station area 21, acoverage area of a sector antenna 2022 in the base station area 22, anda coverage area of the sector antenna 2031 in the base station area 23.

Similarly, a coverage area of the sector antenna 2041 of the basestation area 24 is adjacent to coverage areas of the sector antennas2042 and 2043 in the base station area 24, and a coverage area of thesector antenna 2023 in the base station area 22.

The above mentioned method is a method to visually find a neighboringantenna area. However, such method can be applied only under a limited(or ideal) condition in which a structure that blocks a radio wave, astructure that reflects a radio wave or the like does not exist in acoverage area of each sector antenna.

Accordingly, in order to overcome such restrictions, the applicantproposes the following method for example, in Japanese PatentApplication No. 2006-127387.

That is, it is noted that Japanese Patent Application No. 2006-127387filed May 1, 2006 is herein incorporated by reference.

More specifically, in the method, an adjacent situation between basestation apparatuses is judged by a statistical processing of a wirelesscondition that is reported from a mobile terminal, and an expected pathconnecting a base station apparatus to a sector antenna is dynamicallychanged according to data (i.e. adjacent cell information) generatedbased on this judgment result.

That is, the method according to Japanese Patent Application No.2006-127387 discloses following processes.

A network control apparatus which controls a plurality of base stationapparatuses judges an adjacent situation between the plurality of basestation apparatuses based on reception intensity of signals from theplurality of base station apparatuses that is transmitted from a mobileterminal.

More specifically, in the method, the network control apparatus judgesan adjacent situation by following procedures. That is:

With respect to each of a plurality of base station apparatuses,reception intensity of signals from base station apparatuses that istransmitted from a mobile terminal is classified into three levels froma first level to a third level in descending order of receptionintensity based on two threshold values;

Two base station apparatuses are selected among the plurality of basestation apparatuses;

When the reception intensities of signals from two selected base stationapparatuses corresponds to the first level, it is judged that the twobase station apparatuses are “a pair of close base station apparatuses”that have a positional relationship in which two base stationapparatuses exist close to each other for a spatial distance of apropagation, on the other hand;

When one of reception intensities of signals from the two base stationapparatuses corresponds to the first level and the other corresponds tothe second level, it is judged that the two base station apparatuses are“a pair of adjacent base station apparatuses” that have a positionalrelationship in which a spatial distance of a propagation between thetwo base station apparatuses is larger than that of the pair of closebase station apparatuses.

FIG. 3 is a figure illustrating a state in which a plurality of mobileterminals that are connected with a part of base station apparatuses areconnected by the maximum ratio combining (MRC) in a mobilecommunications system exemplarily illustrated in FIG. 1 and FIG. 2.

As shown in FIG. 3, in the exemplary embodiment, the mobile terminal1011 is connected to the base station apparatuses 2011 and 2021. Signalsreceived by the two base station apparatuses 2011 and 2021 aretransferred to the maximum ratio combining point (MRC-P) 3051 providedfor the mobile terminal 1011. The maximum ratio combining point 3051performs a decoding process based on a signal received from the mobileterminal 1011.

On the other hand, the mobile terminal 1012 is connected to the basestation apparatuses 2021 and 2031. Respective signals received by thebase station apparatuses 2021 and 2031 are transferred to the maximumratio combining point (MRC-P) 3052 provided for the mobile terminal1012. The maximum ratio combining point 3052 performs a decoding processbased on a signal received from the mobile terminal 1012.

Further, in an example shown in FIG. 3, in order to clearly express aconnection relationship among the mobile terminal, the base stationapparatus and the maximum ratio combining point, each node is directlyconnected with each other, for convenience of explanation. However, inan actual situation, as shown in FIG. 1, each node forms a network thatcan be connected arbitrarily. Then, the base station apparatus 2021 isconnected with the mobile terminals 1011 and 1012. A signal received bythe base station apparatus 2021 is transferred to the maximum ratiocombining points 3051 and 3052. In the exemplary embodiment, “broadcastfunction” that is a network function can be used for the transfer.

As mentioned above, the maximum ratio combining points (MRC-P305, 3051and 3052) according to the exemplary embodiment can take in a requiredoutput from an arbitrary base station apparatus. The maximum ratiocombining point only associates a base station apparatus therewith byusing the “broadcast function” regardless of an increase or decrease ofmobile terminals under communication (i.e. mobile terminals which arebusy). For this reason, in the exemplary embodiment, a line settingbetween a base station apparatus and a maximum ratio combining point isnot necessary.

FIG. 4 is a figure exemplarily illustrating a situation in which amaximum ratio combining point and a selection combining point areaccommodated together in a physical apparatus in a mobile communicationssystem according to an exemplary embodiment of the present invention.

In FIG. 4, the base station apparatuses 2011, 2021, 2031 and 2041 areconnected to a network formed by the high speed line 1001 and the lowspeed line 1002 as shown in FIG. 1. On the other hand, the maximum ratiocombining point (MRC-P) and the selection combining point (SC-P) areaccommodated in an apparatus which exists physically.

Specifically, the maximum ratio combining points 3051 and 3052 and theselection combining point 3061 are accommodated in a first apparatus.The maximum ratio combining points 3053 and 3054 and the selectioncombining point 3062 are accommodated in a second apparatus. The firstand second apparatuses are ones of apparatuses connected to the network.That is, the first and/or second apparatuses may be stand-alone. Thefirst and/or second apparatuses may be accommodated in any one of thebase station apparatus, the radio network controller (RNC), anotherexternal apparatus or the like when the apparatuses can be connected toa network.

FIG. 5 is a figure exemplarily illustrating a connection state of amobile terminal and a base station apparatus in a mobile communicationssystem according to an exemplary embodiment of the present invention.

FIG. 5 shows an example of a state in which a maximum ratio combiningconnection path between the sector antennas 2012 and 2013 in the basestation area 21 and the base station apparatus 2021 in the base stationarea 22 is formed with respect to the mobile terminal 101.

The maximum ratio combining point 305 is accommodated in a base stationapparatus (i.e. sector base station) 20000 which covers the base stationarea 21. A connection between the sector antenna 2012 and the maximumratio combining point 305 is established by a connection in the basestation apparatus. A connection between the sector antenna 2013 and themaximum ratio combining point 305 is also established by a connection inthe base station apparatus.

The base station apparatus 2021 and the maximum ratio combining point305 are connected to the maximum ratio combining point 305 in the basestation apparatus 20000 via the high speed line 1001.

The maximum ratio combining point 305 is connected to the selectioncombining point 306 via the low speed line 1002 and also is connected tothe radio network controller (RNC) 307 via the low speed line 1002. Themaximum ratio combining point 305 is directly connected to the radionetwork controller 307 via the low speed line 1002. This relation isequal to a form in which all antenna outputs are connected to themaximum ratio combining point 305 in a connection relationship mentionedabove with reference to FIGS. 46A to 46C.

Next, a situation in which signals is actually sent from a plurality ofbase station apparatuses will be described.

FIG. 6 is a figure exemplifying a connection situation of acommunication link between a base station apparatus and a mobileterminal in a mobile communications system according to an exemplaryembodiment of the present invention. FIG. 7 is a figure (table)illustrating a connection situation of a communication link between abase station apparatus and a mobile terminal shown in FIG. 6.

In an example shown in FIG. 6, each of the base station apparatuses2011, 2021, 2031, 2041 and 2051 is a base station apparatus having anomni-antenna (i.e. non-directional antenna). The mobile terminals 1011,1012 and 1013 are arranged in a coverage area of base stationapparatuses as an example shown in FIG. 6. That is, a distancerelationship between a mobile terminal and a base station apparatusesdiffers for each of the mobile terminals 1011, 1012 and 1013 accordingto a position where each of the mobile terminals exist.

More specifically, the mobile terminal 1011 is located at a positionwhere the mobile terminal 1011 can communicate with the base stationapparatuses 2021, 2031 and 2041. The mobile terminal 1012 is located ata position where the mobile terminal 1012 can communicate with the basestation apparatuses 2021, 2041 and 2051. The mobile terminal 1013 islocated at a position where the mobile terminal 1013 can communicatewith the base station apparatuses 2041 and 2051.

At this time, for example, in case of the mobile terminal 1011, a signalsent from the mobile terminal 1011 by an up link is received by the basestation apparatuses 2021, 2031 and 2041. Respective signals received bythe base station apparatuses 2021, 2031 and 2041 are combined by amaximum ratio combining point that is not shown in FIG. 6 (itcorresponds to MRC-P305 in an example shown in FIG. 5). An operation ofthe above mentioned signal combining will be described with reference toFIGS. 8 to 13.

FIG. 8 is a configuration diagram showing a connection situation of acommunication link between a base station apparatus and a mobileterminal exemplarily shown in FIGS. 6 and 7 from a view point of anetwork connection of a mobile communications system. FIG. 9 is a figureillustrating a signal transmission route among a mobile terminal, a basestation apparatus and a maximum ratio combining point in the situationshown in FIGS. 6 to 8.

In FIG. 8, the base station apparatuses 2011, 2021, 2031, 2041 and 2051shown in FIG. 6 are connected to the maximum ratio combining points 3051to 3053 via for example, a bus type network (i.e. high speed line 1001).In an example shown in FIG. 8, the three maximum ratio combining points3051 to 3053 are accommodated in an external apparatus which is arrangedat a physically different location from locations where the base stationapparatuses are arranged on the network. Further, a plurality of maximumratio combining points can be accommodated to a plurality of externalapparatuses, that is, not limited to one external apparatus as mentionedabove.

In such system configuration, a connection relationship between the eachmobile terminal and a base station apparatus and a maximum ratiocombining point to which an output signal of the base station apparatusis transmitted is managed according to a figure (i.e. management table)shown in FIG. 9. That is, in FIG. 9, identification information of amobile terminal, an identification number of a base station apparatusreceiving a signal from the mobile terminal and identificationinformation of a maximum ratio combining point which performs maximumratio combining processing to a signal of the mobile terminal areassociated with each other. The management table is dynamically managedby a radio network controller (307 or line connection controller) thatis not shown in a system block diagram shown in FIG. 8.

Here, the radio network controller 307 is an apparatus which integrallycontrols operations of a plurality of base station apparatuses (2011,2021, 2031, 2041 and 2051) to be managed. That is, the radio networkcontroller dynamically updates a management table exemplified in FIG. 9according to movement of mobile terminals in a coverage area of the eachbase station apparatus. The update operation is performed for example,at a predetermined time cycle. As a result, the each base stationapparatus determines a base station apparatus by which a signal receivedfrom a mobile terminal is transmitted and a maximum ratio combiningpoint to which the signal is transferred.

Further, the management table (FIG. 9) may be kept in for example, theradio network controller 307 and referred to by the five base stationapparatuses according to the need.

In a system configuration shown in FIG. 8, with respect to a connectionsituation of a communication link shown in FIG. 6 and FIG. 7, thefollowing judgment is performed.

That is, a signal from the mobile terminal 1011 is sent to the maximumratio combining point 3051 via the base station apparatuses 2021, 2031and 2041. Similarly, a signal from the mobile terminal 1012 is sent tothe maximum ratio combining point 3052 via the base station apparatuses2021, 2041 and 2051. A signal from the mobile terminal 1013 is sent tothe maximum ratio combining point 3053 via the base station apparatuses2041 and 2051. Then, the each maximum ratio combining point performsmaximum ratio combining processing based on signals received from aplurality of base station apparatuses. In order to realize the mostsuitable maximum ratio combining processing, when receiving packet dataflowing through the high speed line 1001, the each maximum ratiocombining point refers to the management table shown in FIG. 9. Here,the packet data will be described with reference to FIG. 10.

FIG. 10 is a figure exemplifying a format of a data packet when eachbase station apparatus shown in FIG. 6 and FIG. 8 transmits a signalthat is received from a mobile terminal to a network.

As mentioned above with reference to FIG. 1 and FIG. 3, a networkforming a mobile communications system according to the exemplaryembodiment uses a “broadcast function” as an example. The base stationapparatuses 2011, 2021, 2031, 2041 and 2051 produce a data packet withthe format exemplified in FIG. 10 and also transmit the produced datapacket by a “broadcast function” based on a signal received from amobile terminal.

More specifically, the data packet shown in FIG. 10 includes an addressfield and a payload field. The base station apparatuses 2011, 2021,2031, 2041 and 2051 transmit data packets 5011, 5021, 5031, 5041 and5051 to a network, respectively.

That is, the data packet 5011 transmitted by the base station apparatus2011 includes a payload (ANT2011) and an address A (ANT2011). The basestation apparatus 2011 generates digital data based on a wireless signalreceived from a mobile terminal and also sets the generated digital datain the payload (ANT2011).

Here, digital data generated by the each base station apparatus is thedigital data which is obtained by applying only a demodulation to areceived wireless signal by using an RF circuit or the like, and towhich despread processing has not been applied yet. This is because, aseries of a maximum ratio combining processing including despreadprocessing is performed in a maximum ratio combining point based on thedigital data. In the exemplary embodiment, as exemplified in FIG. 8,each base station apparatus and a maximum ratio combining point arearranged at geographically different locations and connected with eachother via the high speed line 1001. The configuration of the basestation apparatus differs from that of a base station apparatus such asa conventional sector base station.

Even when such system configuration is used, with respect to atransmission band (i.e. information capacity), the high speed line 1001has to have a wide transmission band that is at least equal to or morethan a transmission rate of code information transmitted in a wirelesssection in order to realize appropriate maximum ratio combiningprocessing at a maximum ratio combining point. This condition should besatisfied regardless of the number of base station apparatuses andmaximum ratio combining points accommodated in the high speed line 1001.Therefore, it is desirable that a transmission rate of the high speedline 1001 should assure a transmission rate that is several times of atransmission rate of code information transmitted in a wireless section.

As such broadband transmission line, for example, an optic fiber can beused. In the exemplary embodiment, for example, a technique of Radio onFiber (RoF) can be employed in which a wireless signal is transmittedwithout changing its form in a broadband transmission line using anoptic fiber.

The base station apparatus 2011 sets an address (i.e. identificationinformation) that is assigned to an own apparatus in advance into anaddress A (ANT2011). As a result, the data packet 5011 transmitted witha “broadcast function” of the base station apparatus 2011 will becompleted. By a similar procedure, four other base station apparatusesalso produce data packet, respectively.

By referring to the management table shown in FIG. 9, the maximum ratiocombining points (3051, 3052 and 3053) judge a data packet which shouldbe taken in among data packets 5011, 5021, 5031, 5041 and 5051 whichflow through the high speed line 1001, respectively. This judgment iscarried out by performing a comparison between an address in an addressfield of each data packet and an identification number of a base stationapparatus stored in the management table. The each maximum ratiocombining point performs maximum ratio combining processing by referringto a payload included in a data packet which has been taken in,according to the above judgment. A series of the operations will bedescribed with reference to FIGS. 11 to 13.

Further, in a configuration diagram of each mobile communications systemshown in FIG. 11 and in successive figures, in order to simplify acontent of a drawing, the radio network controller (RNC) 307 is notshown. However, in an actual operation, the radio network controller 307determines a final operation of each node in a mobile communicationssystem.

FIG. 11 is a figure illustrating a situation in which a signal receivedby each base station apparatus is taken in the specific maximum ratiocombining point 3053 with respect to a connection relationship among amobile terminal, a base station apparatus and a maximum ratio combiningpoint shown in FIG. 6, FIG. 8 and FIG. 9. That is, for convenience ofexplanation, FIG. 11 shows the situation in which only a signal from themobile terminal 1011 is received by the each base station apparatus.Further, a case in which one base station apparatus receives signalsfrom a plurality of mobile terminals is described below with referenceto FIG. 13.

As shown in FIG. 9, the maximum ratio combining point 3051 is requiredto receive a signal transmitted from the mobile terminal 1011, from thebase station apparatuses 2021, 2031 and 2041. Accordingly, the maximumratio combining point 3051 takes in only data packets 5021, 5031 and5041 that are transmitted with a broadcast function of the three basestation apparatuses about the mobile terminal 1011 based on informationin a management table shown in FIG. 9 as conceptually shown in FIG. 11.The maximum ratio combining points 3052 and 3053 similarly perform aseries of such operations by referring to information in the managementtable although a data packet for these maximum ratio combining points isnot shown in FIG. 11.

Here, an internal configuration of one of the maximum ratio combiningpoints 3051, 3052 and 3053 mentioned above will be described withreference to FIG. 12.

FIG. 12 is a block diagram showing an internal configuration of themaximum ratio combining point 3051 among three maximum ratio combiningpoints shown in FIG. 11.

As shown in FIG. 12, the maximum ratio combining point 3051 includes asan example, three RAKE fingers 4012 to 4014 (RAKE1,RAKE2,RAKE3) and amaximum ratio combiner (CMB) 4015 therein. The RAKE fingers 4012, 4013and 4014 are connected to the base station apparatuses 2021, 2031 and2041, respectively. The each RAKE finger performs synchronous detectionprocessing including despread processing based on digital data in apayload field of a data packet received from respective base stationapparatuses. When signals from a plurality of mobile terminals aresuperimposed on the received digital data, the RAKE fingers 4012 to 4014also discriminate a signal of a specific mobile terminal. The maximumratio combiner 4015 performs a combining of signals from the mobileterminal 1011 by performing maximum ratio combining processing based onthe output signals of the RAKE fingers 4012, 4013 and 4014. A generalmethod can be used for the maximum ratio combining processing.Therefore, in the exemplary embodiment, a detailed description aboutmaximum ratio combining processing itself will be omitted.

FIG. 13 is a figure illustrating a situation in which a signal receivedby each base station apparatus is taken in the specific maximum ratiocombining points 3051 and 3052 with respect to a connection relationshipamong a mobile terminal, a base station apparatus and a maximum ratiocombining point shown in FIG. 6, FIG. 8 and FIG. 9. In FIG. 13, signalsfrom a plurality of mobile terminals are received by one base stationapparatus. This is a difference between the state shown in FIG. 13 andthe state shown in FIG. 11 mentioned above.

With respect to the mobile terminal 1011 and the mobile terminal 1012shown in FIG. 13, a series of operations for a signal combining is alsoperformed by referring to information in the management table shown inFIG. 9. That is, in FIG. 13, a signal transmitted from the mobileterminal 1011 and a signal transmitted from the mobile terminal 1012 arereceived by a plurality of base station apparatuses 2021, 2031, 2041 and2051.

The base station apparatus 2021 produces a data packet 5021 based onsignals received from the mobile terminal 1011 and the mobile terminal1012. The base station apparatus 2021 transmits the produced data packet5021 to the high speed line 1001. The base station apparatus 2031produces a data packet 5031 based on a signal received from the mobileterminal 1011. The base station apparatus 2031 transmits the produceddata packet 5031 to the high speed line 1001. Similarly, the basestation apparatuses 2041 and 2051 also transmit produced data packets5041 and 5051 to the high speed line 1001.

That is, in the state shown in FIG. 13, a signal in which signals from aplurality of mobile terminals 1011 and 1012 are superimposed reaches thebase station apparatuses 2021 and 2041. This is a difference between thestate shown in FIG. 13 and the state shown in FIG. 11. In such a case,the base station apparatuses 2021 and 2041 set digital data in whichsignals from a plurality of mobile terminals are superimposed into apayload field of a data packet to be produced. The base stationapparatuses 2021 and 2041 transfer the data packet to the maximum ratiocombining points 3051 and 3052. The maximum ratio combining points 3051and 3052 independently perform processing for each mobile terminal usinga plurality of RAKE fingers based on a received data packet as mentionedabove with reference to FIG. 12.

More specifically, data packets in which signals from the mobileterminal 1011 and the mobile terminal 1012 are superimposed are a datapacket 5021 and a data packet 5041. The data packets are distributed toboth of the maximum ratio combining point 3051 which combines a signalof the mobile terminal 1011 and the maximum ratio combining point 3052which combines a signal of the mobile terminal 1012 to be supplied toRAKE fingers provided in the respective maximum ratio combining points.Thus, the each base station apparatus uses information in the managementtable shown in FIG. 9 and as a result, a signal received by the eachbase station apparatus is taken in by a maximum ratio combining pointwhich needs a signal received by the base station apparatus.

Next, an ideal case in which not only a maximum ratio combining pointbut also a selection combining point is connected to a network will bedescribed with reference to FIGS. 14 to 22.

FIG. 14 is a figure illustrating a situation in which signals receivedby the base station apparatuses 2031 and 2041 are taken in by thespecific maximum ratio combining points 3051 and then an output of themaximum ratio combining point and a signal received by the base stationapparatus 2021 are taken in by a specific selection combining point3061, with respect to a connection relationship among a mobile terminal,a base station apparatus and a maximum ratio combining point shown inFIG. 4, FIG. 6 and FIG. 9.

In an example described above with reference to FIG. 11, only a maximumratio combining point combines signals from a mobile terminal. Incontrast, in an example shown in FIG. 14, in a system configuration of amobile communications system, a maximum ratio combining point and aselection combining point coexist on a network. That is, in the exampleshown in FIG. 14, not only a signal combining is performed to a signalfrom a mobile terminal by the maximum ratio combining point (MRC-P), butalso a signal combining is further performed using the combined signaland a signal received by another base station apparatus by a selectioncombining point (SC-P).

Here, in order to make a description of FIG. 14 easy, it is assumed thatsignals from the base station apparatuses 2031 and 2041 can be sent tothe maximum ratio combining point 3051 and meanwhile, a signal from thebase station apparatus 2021 cannot be sent to the maximum ratiocombining point 3051.

FIG. 15 shows a signal destination in a connection situation shown inFIG. 14. A basic configuration of a management table shown in FIG. 15 isequal to a configuration of the management table shown in FIG. 9mentioned above and moreover, information about the selection combiningpoint (SC-P) is included. This is a difference between a configurationof the management table shown in FIG. 15 and a configuration of themanagement table shown in FIG. 9. That is, by using FIG. 15, it is knownwhich output signal of a base station apparatus should be used formaximum ratio combining processing among output signals of base stationapparatuses which receive a signal from a mobile terminal. Moreover, byusing FIG. 15, a processing result of maximum ratio combining processingand an output signal of a base station apparatus that should be used forselection combining processing can be known.

More specifically, in a distribution state shown in FIG. 6, a signaltransmitted from the mobile terminal 1011 has been received by aplurality of base station apparatuses 2021, 2031 and 2041. An example(i.e. management table) shown in FIG. 15 that is corresponding to theabove distribution state represents the following state.

That is, the base station apparatuses 2031 and 2041 receive a signalfrom the mobile terminal 1011. The base station apparatus 2031 and 2041transmit a data packet corresponding to a received signal to the maximumratio combining point 3051. On the other hand, the base station 2021receives a signal from the mobile terminal 1011. The maximum ratiocombining point 3051 transmits a signal that is a combining result tothe selection combining point 3061. The base station apparatus 2021transmits a data packet corresponding to a received signal to theselection combining point 3061.

FIG. 16 shows a format of a data packet for sending a signal of a mobileterminal to a maximum ratio combining point and a selection combiningpoint via a base station apparatus.

In FIG. 16, a data packet 5121 shows a packet used in a case in which asignal from the mobile terminal 1011 that is received by the basestation apparatus 2011 is sent to the selection combining point 3061. Adata packet 5201 shows a packet used in a case in which a result of asignal combining by the maximum ratio combining point 3051 is sent tothe selection combining point 3061.

Further, the maximum ratio combining point 3051 performs maximum ratiocombining processing before producing the data packet 5201. The maximumratio combining point 3051 performs maximum ratio combining processingwith respect to the mobile terminal 1011 by using the data packets 5031and 5041 which are produced by the base station apparatuses 2031 and2041 according to a procedure mentioned above with reference to FIG. 9and FIG. 10.

Considering the above data packets 5121 and 5201, the state in which asignal from the mobile terminal 1011 is transferred to a base stationapparatus, a maximum ratio combining point and a selection combiningpoint is described with reference to FIG. 14.

In FIG. 14, a signal transmitted from the mobile terminal 1011 isreceived by the plurality of base station apparatuses 2021, 2031 and2041. The base station apparatus 2031 produces the data packet 5031 andtransmits the produced data packet to the high speed line 1001.Similarly, the base station apparatus 2041 transmits the produced datapacket 5041 to the high speed line 1001. The maximum ratio combiningpoint 3051 receives the data packets 5031 and 5041 with the sameprocedure as described in the case of the management table shown in FIG.9 mentioned above. The maximum ratio combining point 3051 performsmaximum ratio combining processing by using three RAKE fingers or thelike shown in FIG. 12. The maximum ratio combining point 3051 producesthe data packet 5201 mentioned above based on a processing result of themaximum ratio combining processing and transmits the produced datapacket to the low speed line 1002. The selection combining point 3061receives the data packet 5201 by referring to the management table shownin FIG. 15 with the same procedure as described in the case of themanagement table shown in FIG. 9 mentioned above.

On the other hand, a data packet 5121 produced by the base stationapparatus 2021 is transmitted to the low speed line 1002. The selectioncombining point 3061 receives the data packet 5121 by referring to themanagement table shown in FIG. 15 with the same procedure as describedin the case of the management table shown in FIG. 9 mentioned above.

The selection combining point 3061 performs selection combiningprocessing using the data packets 5201 and 5121 as an input signal.

A data packet produced by each base station apparatus may be transmittedby appropriately changing its destinations to a maximum ratio combiningpoint and to a selection combining point according to a distributionstate of mobile terminals in a coverage area of each base stationapparatus or a construction or a dismantlement of a structure locatedaround each coverage area. In this case, a destination of a data packetproduced by the respective base station apparatuses needs to be changedto a maximum ratio combining point or a selection combining point whilea user makes a telephone call by using a mobile terminal (that is, whilethe data packet is constantly transferred). Accordingly, in thefollowing description, a case in which such change is performed will bedescribed.

(Change from the Selection Combining (SC) to a Maximum Ratio Combining(MRC))

First, a case in which such change is realized will be described usingFIG. 14 and FIGS. 17 to 19. Further, FIG. 14 and FIGS. 17 to 19exemplify a change process in which a destination of a signal from abase station apparatus is changed from the selection combining (SC) to amaximum ratio combining (MRC).

That is, in the above mentioned situation shown in FIG. 14, maximumratio combining processing is applied to a signal received by the basestation apparatuses 2031 and 2041, and selection combining processing isapplied to a result of the maximum ratio combining processing and asignal received by the base station apparatus 2021. In the followingdescription, the situation mentioned above, a situation shown in FIG. 17and FIG. 18 and a final situation shown in FIG. 19 will be described. Inthis case, in the situation shown in FIG. 19, with respect to a signalof the mobile terminal 1011, maximum ratio combining processing isperformed based on signals received by the base station apparatuses2021, 2031 and 2041. Hereinafter, a series of transitions will bedescribed in order.

FIG. 17 is a figure showing a situation in which the data packet 5121 tobe transferred to the selection combining point 3061 and a data packet5021 to be transferred to the maximum ratio combining point 3051 aretransmitted from the base station apparatus 2021.

In the situation shown in FIG. 14, the base station apparatus 2021transmits only the data packet 5121. In contrast, in FIG. 17, the basestation apparatus 2021 produces the data packet 5121 subsequently andalso produces the data packet 5021 to be transferred to the maximumratio combining point 3051. The base station apparatus 2021 itselfjudges whether or not both of the data packet 5021 and the data packet5121 should be produced based on a change control using a thresholdvalue. This change control will be described below with reference toFIG. 25 and successive figures. In the situation, the data packet 5021is transferred with the broadcast function mentioned above to aconnection end of the maximum ratio combining point 3051.

However, at this time, the maximum ratio combining point 3051 does nottake in the data packet 5021 yet. That is, the maximum ratio combiningpoint 3051 performs a maximum ratio combining using only signals fromthe base station apparatuses 2031 and 2041 mentioned above withreference to FIG. 14 and also transfers the produced data packet 5201 tothe selection combining point 3061. An operation state at this time isthe same as that of the situation shown in FIG. 14. That is, theselection combining point 3061 takes in the data packets 5121 and 5201.On the other hand, the maximum ratio combining point 3051 takes in thedata packets 5031 and 5041.

FIG. 18 is a figure showing a situation until the data packet 5021 istaken in the maximum ratio combining point 3051 from the situation shownin FIG. 17.

In the situation shown in FIG. 18, the maximum ratio combining point3051 starts to take in the data packet 5021 from the base stationapparatus 2021 in order to become operable, after referencing themanagement table. The maximum ratio combining point 3051 performsmaximum ratio combining processing using three signals from the basestation apparatuses 2021, 2031 and 2041 by taking in the data packet5021. As a result, the maximum ratio combining point 3051 produces thedata packet 5201 and transfers the produced data packet to the selectioncombining point 3061. According to the processes, the selectioncombining point 3061 takes in the data packets 5021 and 5201. On theother hand, the maximum ratio combining point 3051 takes in the datapackets 5021, 5031 and 5041.

FIG. 19 is a figure showing a situation until a use of a selectioncombining point is stopped from the situation shown in FIG. 18.

In the situation shown in FIG. 18 mentioned above, signals of basestation apparatuses (that is, each signal from the base stationapparatuses 2021, 2031 and 2041) to be combined by the maximum ratiocombining point 3051 are taken in the maximum ratio combining point3051. For this reason, the base station apparatus 2021 does not need tosend the data packet 5121 to the selection combining point 3061. Thebase station apparatus 2021 stops a production and transfer of the datapacket 5121 according to a judgment result that is judged by the radionetwork controller 307 in consideration of “change request processing”that is described below with reference to FIG. 25 and successive figuresand “operation change control” based on the change request processing.Here, the judgment result is a judgment showing that selection combiningprocessing is unnecessary (release request of MRC setting).

The maximum ratio combining point 3051 does not need to send the datapacket 5201 to the selection combining point 3061. That is, at thistime, the base station apparatus 2021 stops a production and transfer ofthe data packet 5121. The maximum ratio combining point 3051 stops aproduction and transfer of the data packet 5201. As a result, theselection combining point 3061 becomes unused.

Here, the following procedure is used to stop a production and transferof the data packet as mentioned above. That is, by referring to amanagement table shown in FIG. 15, the maximum ratio combining point3051 and the selection combining point 3061 can operate in cooperationwith each other. Accordingly, the maximum ratio combining point 3051starts maximum ratio combining processing according to a confirmation ofa reception of all data packets with respect to the base stationapparatuses 2021, 2031 and 2041 and also notifies the selectioncombining point 3061 of information showing that a data packet from thebase station apparatus 2021 is not needed anymore. This notification isdelivered through for example, a control line not shown in FIG. 19 orother figures (i.e. a control line 10005 shown in FIG. 25).

(Change from a Maximum Ratio Combining (MRC) to the Selection Combining(SC))

Next, in order to change a combining method from a maximum ratiocombining (MRC) to the selection combining (SC), a destination of asignal from a certain base station apparatus is changed to the selectioncombining point 3062. This change process will be described withreference to FIGS. 20 to 22.

More specifically, the base station apparatus 2041 and the base station2051 that receive a signal of the mobile terminal 1012 outputs a datapacket. FIGS. 20 to 22 exemplarily show a case in which a destination ofthe data packet outputted from the base station apparatuses is changedfrom the maximum ratio combining point 3052 to the selection combiningpoint 3062.

FIG. 20 shows a situation in which maximum ratio combining processing isperformed based on a signal of the mobile terminal 1012 that is receivedby the base station apparatuses 2041 and 2051.

In a situation shown in FIG. 20, a signal of the mobile terminal 1012 isreceived by the base station apparatuses 2041 and 2051. The base stationapparatuses 2041 and 2051 produce the data packets 5041 and 5051 to betransferred to the maximum ratio combining point 3052 based on areceived signal. The data packets are also transmitted to the high speedline 1001 with a broadcast notification like the case mentioned above.The maximum ratio combining point 3052 performs an acquisition of thedata packets 5041 and 5051 and maximum ratio combining processing by thesame procedure as mentioned above.

At this time, the maximum ratio combining point 3052 and the selectioncombining point 3062 are connected with each other via the low speedline 1002. The data packet 5201 is transferred from the maximum ratiocombining point 3052 to the selection combining point 3062 like the caseshown in FIG. 17.

FIG. 21 is a figure showing a situation in which the base stationapparatuses 2041 and 2051 produce data packets 5041 and 5051 to betransferred to the maximum ratio combining point 3052 and data packets5141 and 5151 to be transferred to a selection combining point 3062.

As shown in FIG. 21, the base station apparatus 2041 produces point 3062in addition to the data packet 5041 in the situation shown in FIG. 20.The base station apparatus 2041 transmits the data packets 5041 and 5141to the high speed line 1001. Similarly, the base station apparatus 2051produces the data packet 5151 to be transferred to the selectioncombining point 3062 in addition to the data packet 5051 in thesituation shown in FIG. 20. The base station apparatus 2051 transmitsthe data packets 5051 and 5151 to the high speed line 1001. The basestation apparatuses 2041 and 2051 itself judges whether or not both ofthe data packets 5021, 5121 and the data packets 5051, 5151 should beproduced based on a change control using a threshold value. The changecontrol will be described later with reference to FIG. 25 and successivefigures.

In the situation shown in FIG. 20, the selection combining point 3062determines that it is not necessary to take in any data packet from abase station apparatus. This determination is also performed byreferring to a management table mentioned above. In contrast, accordingto a change of content by an updating of the management table, asituation is transferred to the situation shown in FIG. 21. That is, theselection combining point 3062 starts to take in the data packets 5141and 5151. The selection combining point 3062 starts to perform selectioncombining processing using the data packets 5141 and 5151.

FIG. 22 is a figure showing a situation until a use of a maximum ratiocombining point is stopped from the situation shown in FIG. 20.

In the situation shown in FIG. 21, the selection combining point 3062instructs the maximum ratio combining point 3052 to stop an operation byconfirming that the data packets 5141 and 5151 are normally received andselection combining processing is started. Moreover, the base stationapparatus 2041 and 2051 stop a production and transfer of the datapackets 5041 and 5051 according to a judgment result that is judged bythe radio network controller 307 in consideration of “change requestprocessing” that will be described later with reference to FIG. 25 andsuccessive figures and “operation change control” based on the changerequest processing. Here, the judgment result indicates that selectioncombining processing is unnecessary (i.e. release request of MRCsetting).

By applying a procedure described above, in the exemplary embodiment, ina mobile communications system in which the selection combining point(SC-P) and the maximum ratio combining point (MRC-P) are used, theselection combining (SC) and a maximum ratio combining (MRC) aredynamically changed.

Next, dynamic change processing which is performed based on a changeprocedure mentioned above in many base station apparatuses which form alarge service area will be described with reference to FIG. 23 and FIG.24.

FIG. 23 is a figure showing a distribution of a mobile terminal undercommunication (i.e. a mobile terminal which is busy) at a time (t1).FIG. 24 is a figure showing a distribution of a mobile terminal undercommunication at a different time (t2).

In FIG. 23 and FIG. 24, fifteen base station apparatuses 2011, 2021,2031, 2041, 2051, 2061, 2071, 2081, 2091, 2101, 2111, 2121, 2131, 2141and 2151 form a base station area (service area). In FIG. 23 and FIG.24, each regular hexagon schematically represents a base station areaformed by one base station apparatus. The each base station apparatussupports a wireless communication performed by a mobile terminal locatedin a coverage area of an own apparatus. In FIG. 23 and FIG. 24, areference mark is not given to each mobile terminal from convenience ofexpression in a drawing. However, mobile terminals are distributed in acoverage area of the each base station apparatus as shown in FIG. 23 andFIG. 24.

Further, in FIG. 23 and FIG. 24, a base station apparatus which iscolored in black is a base station apparatus which selects a maximumratio combining (MRC).

As shown in FIG. 23, suppose that at the time (t1), in a coverage areaof each base station apparatus, a mobile terminal is under communicationas below. That is, in each coverage area of the base station apparatuses2011, 2021, 2041, 2071, 2081, 2091, 2121, 2131, 2141 and 2151, onemobile terminal is under communication. In each coverage area of thebase station apparatuses 2101 and 2111, two mobile terminals are undercommunication. In each coverage area of the base station apparatuses2031 and 2061, three mobile terminals are under communication. In acoverage area of the base station apparatus 2051, six mobile terminalsare under communication.

When overlooking (bird's eye view) the situation shown in FIG. 23, it isobserved that many mobile terminals are distributed in and around acoverage area of base station area 2051. Generally, with respect tosignals of base station apparatuses which are arranged at geographicallydifferent locations, as mentioned above in “BACKGROUND ART”, maximumratio combining processing is not applied and selection combiningprocessing is applied. In contrast, in a mobile communications systemaccording to the exemplary embodiment, a plurality of base stationapparatuses which are arranged at geographically different locations andthe maximum ratio combining point (MRC-P) are connected with each otherby a broadband communication line that is not shown in FIG. 23 (itcorresponds to the high speed line 1001 mentioned above). By using suchsystem configuration, in the exemplary embodiment, maximum ratiocombining processing can be performed between arbitrary base stationapparatuses.

It has been known that there is a difference in a reception efficiencybetween the selection combining (SC) and a maximum ratio combining (MRC)when a signal transmitted from a mobile terminal is received in acommunication line from the mobile terminal to a base station apparatus(that is, an up link). That is, a reception by a maximum ratio combining(MRC) excels in reception efficiency. Thus, a transmission power thatassures the same quality (i.e. bit error rate) can be reduced. It meansthat a channel capacity of an up link in a cell in which a mobileterminal exists can be increased by reducing a transmission power of amobile terminal. This is one of the reasons that a maximum ratiocombining is used between base station apparatuses which are arranged atgeographically different locations in the exemplary embodiment.

By the reason mentioned above, in the distribution situation shown inFIG. 23, suppose that a reception using a maximum ratio combining (MRC)is selected between the base station apparatus 2051 and the base stationapparatuses 2021, 2031, 2041, 2061, 2081 and 2091 that are adjacent tothe base station apparatus 2051 at the time (t1). According to theexemplary embodiment, a transmission power of a mobile terminal locatedin each coverage area of such a plurality of base station apparatusescan be reduced. As a result, since an interference power to other mobileterminals can be reduced, a communication with more mobile terminals canbe realized in comparison to a case of the selection combining (SC).

Next, as shown in FIG. 24, in a coverage area of each base stationapparatus at another time (t2), a distribution situation of a mobileterminal is changed from the distribution situation at the time (t1)mentioned above and the following mobile terminals are undercommunication.

That is, in each coverage area of the base station apparatuses 2011,2031, 2041, 2061, 2071, 2091, 2121 and 2151, one mobile terminal isunder communication. In each coverage area of the base stationapparatuses 2021, 2051 and 2131, two mobile terminals are undercommunication. In a coverage area of the base station apparatus 2111,three mobile terminals are under communication. In each coverage area ofthe base station apparatuses 2081 and 2141, four mobile terminals areunder communication. In a coverage area of the base station apparatus2101, seven mobile terminals are under communication.

When overlooking (bird's eye view) the situation shown in FIG. 24 likethe case shown in FIG. 23, many mobile terminals are distributed in andaround a coverage area of the base station area 2101. In this case, bythe same reason as the case mentioned above with reference to FIG. 23,maximum ratio combining (MRC) is performed between the base stationapparatus 2101 and the base station apparatuses 2071, 2081, 2111, 2131and 2141 that are adjacent to the base station apparatus 2101. That is,base station apparatuses using maximum ratio combining (MRC) changescontinuously, for example, from the state shown in FIG. 23 to the stateshown in FIG. 24. A change process performed during the change will bedescribed later with reference to FIG. 25 and successive figures.

In the state shown in FIG. 24, a plurality of base station apparatusesto which a maximum ratio combining is selected can obtain the sameeffect as mentioned above. Therefore, according to the exemplaryembodiment, since an interference power to other mobile terminals can bereduced, a communication with more mobile terminals can be realized incomparison to a case of the selection combining (SC).

A change of a distribution state of mobile terminals as exemplified inFIG. 23 and FIG. 24 is usually occurred in a mobile communicationssystem in which each mobile terminal moves with a user every moment. Forexample, a distribution state of mobile terminals changes greatly by thefollowing external factors as exemplarily shown below. That is:

a certain time in a day, for example, during working time and afterworking time;

week day and weekend or holiday;

Monday to Friday and Saturday or Sunday; or

an event or entertainment held temporarily to which a large number ofusers will be expected to gather.

That is, it is very desirable to reduce a transmission power of a mobileterminal by applying maximum ratio combining processing to all basestation apparatuses because it allows increase of the number of mobileterminals which can be accommodated, increase of the number of mobileterminals which can perform a communication at the same time andimprovement of a data transfer rate. However, it is difficult to applymaximum ratio combining processing to all base station apparatuses froma view point of a consumption band of a backbone line. Accordingly, inthe exemplary embodiment, maximum ratio combining processing is appliedaggressively to only a base station apparatus which includes many mobileterminals in coverage area thereof and maximum ratio combiningprocessing is not applied to the other base station apparatuses.

Accordingly, a communication system including many mobile terminals canbe realized by dynamically applying maximum ratio combining processingto a base station apparatus to process a transmission signal of aplurality of mobile terminals according to a change in a distributionstate of mobile terminals by considering various external factors(surrounding circumstances such as whether or not an event is held,difference in the time or the day of the week etc.) mentioned above.

Further, a change process will be described later with reference to FIG.25 and successive figures.

<Change Request Processing in a Base Station Apparatus>

Hereinafter, an apparatus configuration for performing dynamic changebetween maximum ratio combining processing (MRC) and selection combiningprocessing (SC) mentioned above will be described. In the exemplaryembodiment, each base station apparatus performs change requestprocessing described below in order to realize a dynamic changeoperation mentioned above.

(Configuration of a Base Station Apparatus)

First, a configuration of a base station apparatus which is connected toa mobile communications system in a description mentioned above will bedescribed.

FIG. 25 is a block diagram exemplarily illustrating an internalconfiguration of a base station apparatus according to the exemplaryembodiment.

A base station apparatus 10000 shown in FIG. 25 includes an antenna10001, a transceiver module 10002, a Central Processing Unit (CPU) 10003and a storage medium 10004. The base station apparatus 10000 isconnected to the high speed line 1001, the low speed line 1002 and acontrol line (CNT) 10005 for performing a communication of a controlsignal with an external apparatus. Here, the external apparatusrepresents a maximum ratio combining point (MRC-P), a selectioncombining point (SC-P), a radio network controller (RNC) or the like ina mobile communications system mentioned above.

The transceiver module 10002 is a general wireless communication unitwhich transmits/receives a wireless signal to/from a mobile terminal viathe antenna 10001. However, in the exemplary embodiment, the transceivermodule 10002 does not perform despread processing of a received signalfrom a mobile terminal.

The CPU 10003 performs an overall operation of the base stationapparatus 10000 including the transceiver module 10002 by executingvarious software programs (computer programs). More specifically, in theexemplary embodiment, the CPU 10003 executes a software program of anevaluation module 100011, a determination module 10012, an MRC reportmodule 10013, a communication control module 10014 and the like byappropriately referring to the storage medium 10004 such as a memory.

The evaluation module 100011 calculates an evaluation value that is aguideline for determining which state is present, a state in which areception by a maximum ratio combining should be applied or a state inwhich a reception by the selection combining should be applied.

The determination module 10012 determines which state is present, astate in which a reception by a maximum ratio combining should beapplied or a state in which a reception by the selection combiningshould be applied, based on the evaluation value calculated by theevaluation module 100011. At the time of the determination, thedetermination module 10012 appropriately refers to the management tableshown in FIG. 9 and FIG. 15 mentioned above via the control line 10005.

The MRC report module 10013 notifies other nodes of a determinationresult by the determination module 10012, via the control line 10005.Here, the other nodes are a neighboring other base station apparatus,the maximum ratio combining point (MRC-P), the selection combining point(SC-P), the radio network controller (RNC) and the like.

The communication control module 10014 produces a data packet which hasa format described with reference to FIG. 10 based on a signal beforedespread processing that is acquired from the transceiver module 10002.The communication control module 10014 transmits the produced datapacket to the high speed line 1001 and/or the low speed line 1002according to the determination result by the determination module 10012.

Further, in the exemplary embodiment, as an example, each moduleexecuted by the CPU 10003 is described as a software program. However,each module shown in FIG. 25 can be recognized as a predeterminedfunctional unit that is realized by a software program and/or hardware.Accordingly, a part of or all of these modules may be realized ashardware.

(Procedure of Change Determination Using an Evaluation Value)

Next, a procedure for determining which state is present, a state inwhich a reception by a maximum ratio combining (MRC) should be appliedor a state in which a reception by the selection combining (SC) shouldbe applied will be described.

FIG. 26 is a figure illustrating a change determination method of signalcombining processing. More specifically, in FIG. 26, a horizontal axisrepresents time. A vertical axis represents an evaluation valuecalculated by the evaluation module 10011. In the exemplary embodiment,as an example, the following three items are used as the evaluationvalue,

an amount of electric power of an up link in a wireless section;

an information rate of an up link in a base station apparatus 10000; and

the number of mobile terminals under communication that exist in acoverage area of the base station apparatus 10000.

A curve of a graph exemplified in FIG. 26 represents a temporal changein a validity of a reception connection by the maximum ratio combining(MRC) which varies according to a state (situation) of mobile terminalswhich exists in a coverage area of the base station apparatus 10000.

In an exemplary embodiment, a determination of whether a reception bythe maximum ratio combining (MRC) should be performed is made by usingtwo threshold values whose values are different. That is, a thresholdvalue 1 shown on a vertical axis shown in FIG. 26 is larger than athreshold value 2 and represents a state in which a use of a maximumratio combining is more desirable. On the other hand, the thresholdvalue 2 represents a state in which a validity of selecting a maximumratio combining is lower than the state of the threshold value 1.

Hereinafter, a change operation will be described with respect to a caseshown in FIG. 26, in which as an example, an amount of electric power ofan up link (up-link electric power amount) is used as an evaluationvalue of a vertical axis. At a time ta, an up-link electric power amountshown by a curve is lower than the threshold value 2. After that, theup-link electric power amount gradually increases as time passes andthen reaches the threshold value 1 at a time tb. At the time, in theexemplary embodiment, an MRC setting section starts by determining thata maximum ratio combining should be selected. After that, the up-linkelectric power amount increases and after that gradually decreases. Inthis decrease stage, the up-link electric power amount becomes smallerthan the threshold value 1. However, at this time, an MRC settingsection is continued. The up-link electric power amounts furtherdecreases and reaches the threshold value 2 at a time tc. At the time,an MRC setting section is released. After that, the up-link electricpower amount shown by the curve increases and decreases again.Therefore, an MRC setting section is set until a time te from a time td.

Thus, in the exemplary embodiment, the threshold value 1 is used as anMRC setting value. On the other hand, the threshold value 2 is used asan MRC release value. By using the threshold value 1 and the thresholdvalue 2, in the exemplary embodiment, a change operation is stabilized.

(Change Request Processing)

Next, change request processing which is actually performed by thedetermination module 10012 based on a procedure mentioned above will bedescribed with reference to FIGS. 27 to 29. A change request processshown in FIGS. 27 to 29 uses three kinds of evaluation value mentionedabove. In the exemplary embodiment, the base station apparatus 10000 mayperform either one of the change request process shown in FIGS. 27 to29. However, if needed, an exemplary embodiment in which a determinationis performed by using a combination of three kinds of evaluation valueor a plurality of other evaluation values is also expected.

FIG. 27 is a flowchart of change request process in which an up-linkelectric power amount is used as an evaluation value. The flowchartshows a processing procedure of a software program which the CPU 10003of the base station apparatus 10000 executes.

In step S11, the CPU 10003 obtains an up-link electric power amount by ageneral method. Step S11 is realized by a function of the evaluationmodule 10011 mainly.

In step S12, the CPU 10003 compares the up-link electric power amountobtained in step S11 with the threshold value 1. When it is judged thatthe up-link electric power amount is equal to or more than the thresholdvalue 1 in step S12, the CPU 10003 starts an MRC setting request (stepS13).

On the other hand, when it is judged that the up-link electric poweramount is smaller than the threshold value 1 in step S12, the CPU 10003compares the up-link electric power amount with the threshold value 1(step S14).

When it is judged that the up-link electric power amount is equal to ormore than the threshold value 2 in step S14, the CPU 10003 continues anMRC setting request (step S13). On the other hand, when it is judgedthat the up-link electric power amount is smaller than the thresholdvalue 2 in step S14, the CPU 10003 releases an MRC setting request (stepS15).

In step S16, the CPU 10003 obtains setting information of a connectionmode from an external apparatus or another module of an own apparatusaccording to a request process in step S13 or step S15 mentioned above.The setting information is information which is obtained from anexternal apparatus (an operation system 10100 (a console panel 10101), acentral apparatus 10201) as a result of operation change controlprocessing (FIGS. 30 to 44) described below or which is decided by abase station apparatus itself. Moreover, in step S16, the CPU 10003reports the obtained setting information of a connection mode to othernodes such as a neighboring other base station apparatus, the maximumratio combining point (MRC-P), the selection combining point (SC-P), theradio network controller (RNC) and the like.

Further, each process in steps S12 to S15 mentioned above is mainlyrealized by a function of the determination module 10012. Each processin step S16 is mainly realized by a function of the report module 10013.

Here, an amount of electric power of an up link (up-link electric poweramount) in a wireless section is one of suitable indexes to evaluate avalidity of a reception connection by a maximum ratio combining and canbe observed in the base station apparatus 10000. Further, a method thatis generally used at present can be employed for calculating an up-linkelectric power amount. For this reason, in the exemplary embodiment, thedetailed description will be omitted.

FIG. 28 is a flowchart of a change request process in which aninformation rate of an up link is used as an evaluation value. Theflowchart shows a processing procedure of a software program which theCPU 10003 of a base station apparatus 10000 executes.

A processing configuration in steps S21 to S26 shown in FIG. 28 is thesame as a processing configuration in steps S11 to S16 shown in FIG. 27mentioned above. For this reason, an overlapped description will beomitted. However, in case of a processing configuration shown in FIG.28, an information rate of an up link is used as an evaluation value.Thus, a comparison object that is compared with each threshold value instep S22 and step S24 is different from a comparison object in step S12and step S14 mentioned above.

Here, an information rate of an up link in the base station apparatus10000 is an information rate of a signal which flows in the apparatuswith respect to the up link and an index related to the up-link electricpower amount mentioned above. The information rate may be measured by anexternal apparatus other than the base station apparatus 10000. Further,a method that is generally used at present can be employed forcalculating an information rate. For this reason, in the exemplaryembodiment, the detailed description will be omitted.

FIG. 29 is a flowchart of change request process in which the number ofmobile terminals is used as an evaluation value. The flowchart shows aprocessing procedure of a software program which the CPU 10003 of thebase station apparatus 10000 executes.

A processing configuration in steps S31 to S36 shown in FIG. 29 is thesame as a processing configuration in steps S11 to S16 shown in FIG. 27mentioned above. For this reason, an overlapped description will beomitted. However, in case of FIG. 29, the number of mobile terminalsunder communication that exist in a coverage area of the base stationapparatus 10000 is used as an evaluation value. For this reason, acomparison object that is compared with each threshold value in step S32and step S34 is different from a comparison object in step S12 and stepS14 mentioned above.

Here, the number of mobile terminals mentioned above is informationwhich flows in the apparatus and an index related to the up-linkelectric power amount mentioned above. The number of mobile terminalsmay be measured by an external apparatus other than the base stationapparatus 10000. Further, a method that is generally used at present canbe employed for calculating the number of mobile terminals. For thisreason, in the exemplary embodiment, the detailed description will beomitted.

As mentioned above, the base station apparatus 10000 determines avalidity of a reception connection of a maximum ratio combining by aprocedure described by referring to FIGS. 26 to 29. The base stationapparatus 10000 stores a determination result (MRC setting request orrelease request) of determination processing in the storage medium 10004and also reports the determination result to other nodes (another basestation apparatus, a maximum ratio combining point, a selectioncombining point, the radio network controller (RNC) and the like) byusing the function of the MRC report module 10013 via the control line10005.

In this case, the radio network controller (RNC) 307 properly controlsoperations of a plurality of base station apparatuses, a maximum ratiocombining point and a selection combining point by considering settinginformation of a connection mode obtained from each of the base stationapparatuses.

That is, in the exemplary embodiment, the radio network controller 307judges the following three states.

Case 1: a state in which only the low speed line 1002 used for theselection combining is used and a setting for a maximum ratio combining(request of an MRC connection mode) is not made.

Case 2: a state in which only the low speed line 1002 used for theselection combining is used, and also a setting for a maximum ratiocombining (request of the MRC connection mode) is made and an actualline state is not the MRC connection mode.

Case 3: a state in which both of the high speed line 1001 used for amaximum ratio combining and the low speed line 1002 used for theselection combining are used together and a setting for a maximum ratiocombining (request of an MRC connection mode) is made and a state inwhich an actual line is the MRC connection mode.

In the three states (cases 1 to 3), the case 1 represents the situationin which a communication capacity is sufficient. The case 2 representsthe situation in which a communication capacity is becoming tight and aconnection line for a maximum ratio combining (high speed line 1001) hasnot been prepared yet. The case 3 represents the situation in which acommunication capacity is becoming tight and reception efficiency isimproving by providing a connection line for a maximum ratio combining(high speed line 1001).

The radio network controller 307 knows a situation of the mobilecommunications system by judging three states mentioned above. The radionetwork controller 307 determines a conclusive operation of each node bymaking a synthetic judgment based on the recognition result andinformation about a connection mode obtained from each base stationapparatus by an operation change control mentioned below.

Next, a selection method of the SC connection for the selectioncombining and the MRC connection for a maximum ratio combining as acommunication line between a base station apparatus and a mobileterminal will be described. This method is used by the radio networkcontroller 307

In a conventional signal combining, a maximum ratio combining isperformed between a plurality of sectors in one base station apparatus(sector base station) as mentioned in “BACKGROUND ART”. Selectioncombining processing performed between base station apparatuses that arearranged at different locations is carried out by for example, onefunction of a radio network controller. That is, when a communicationline with a mobile terminal is needed, a decision of the SC connectionor the MRC connection is made as follows. Only when a plurality ofantennas which receive a signal from a mobile terminal are sectorantennas provided in one base station apparatus, the MRC connection isselected. The SC connection is selected in other cases. This is aninescapable restriction in a conventional signal combining.

In contrast, in a signal combining according to the exemplary embodimentand each of exemplary embodiments mentioned below, there is norestriction like that. That is, each base station apparatus is connectedto the high speed line 1001 to which the MRC-P is connected and isconnected to the low speed line 1002 to which the SC-P is connected.Each base station apparatus judges whether or not the MRC connection isneeded based on a result of a situation evaluation in a coverage area ofan own apparatus. In the exemplary embodiment, a connection mode changesevery moment according to “change request process” in each base stationapparatus mentioned above and “operation change control” based on thechange request process described below.

For this reason, in the exemplary embodiment, the SC connection and theMRC connection are changed dynamically. However, a change of aconnection is made based on “connection strategy” that indicates how tohandle a mobile terminal under communication in a service area of theradio network controller 307.

For example, when a communication capacity in a coverage area of a basestation apparatus is becoming tight and accordingly, a communicationline becomes lacking, the MRC connection is recommended in order toimprove reception efficiency (reception gain). On the contrary, when theMRC connection is being released because a margin of a communicationcapacity in a coverage area is increasing and an improvement ofreception efficiency (reception gain) is not need, the SC connection isrecommended instead of the MRC connection.

Accordingly, in the exemplary embodiment and its example, the radionetwork controller 307 can judge a selection of the MRC connectionand/or the SC connection if at least setting information of a connectionmode can be obtained from each of base station apparatuses. However, theradio network controller 307 performs a selection judgment of the MRCconnection and/or the SC connection according to a connection strategyof a mobile communications system in order to realize an actual andideal communication environment while comprehensively considering notonly setting information of a connection mode but also three statesmentioned above and information held by an external apparatus (centralapparatus 10201 etc.).

<Operation Change Control Based on Change Request Process>

Next, as described with reference to FIGS. 1 to 24, an actualconfiguration for dynamically changing a combining method to the maximumratio combining (MRC) or the selection combining (SC) according to achange request process (FIGS. 27 to 29) in a base station apparatusmentioned above will be described. In the following description, threekinds of method will be described. A first method (a first example) is amethod in which an operator (operation and maintenance personnel) whomanages a mobile communications system intervenes. A second method (asecond example) is a method in which a change is performed by a centralapparatus (monitor apparatus). A third method (a third example) is amethod in which a change is performed by a base station apparatusitself.

A First Example cl A Method in which an Operator Intervenes)

FIG. 30 is a system block diagram of an exemplary mobile communicationssystem in a first example. A mobile communications system shown in FIG.30 includes an operation system (OPS) 10100, a console panel 10101 and amobile switching center (MSC) 10102 in addition to the systemconfiguration mentioned above with reference to FIG. 1 and FIG. 14.

Further, the operation system (OPS) 10100 and the console panel 10101may be formed in different units or in one unit. In a one unit type, adisplay provided in the operation system 10100 can be used for theconsole panel 10101.

The operation system 10100 may monitor an operation status of an entiresystem and control the system. The console panel 10101 may be aman-machine interface for performing an operation control of the systemby an operator. That is, the console panel 10101 reports an operationstatus of an entire system collected by the operation system 10100 to anoperator. The console panel 10101 sets, in the operation system 10100,an operation of an operator with respect to an operation control of thesystem.

FIG. 31 is a figure showing a flow of a change operation in the firstexample. That is, FIG. 31 is exemplifying a procedure for changing asetting mode of a concerned base station apparatus according to an MRCsetting request reported from each of base station apparatuses.

In the example, a result of a change request process (FIGS. 27 to 29) inthe base station apparatus mentioned above is collected to the operationsystem 10100 by a function of the MRC report module 10013. As a result,information of whether or not an MRC setting request is made isindicated on the console panel 10101 for each of base stationapparatuses. An operator knows a state of each of base stationapparatuses by a content indicated on the console panel 10101. Ifrequired, an operator performs an operation for changing a connectionmode to the console panel 10101. The operation system 10100 controls acorresponding base station apparatus according to an instructionoperation set to the console panel 10101.

FIG. 32 is a figure showing an example of a form of a console panel inthe first example. In the console panel 10101 exemplified in FIG. 32,geographical features (for example, an arrangement state of a main road,a location of a landmark and an arrangement state of a base stationantenna apparatus) of a service area of a mobile communications systemare indicated. In the console panel 10101 that is shown as a sample,eight indication-and-operation switches for a recognition of anevaluation state and a change of a setting state of base stationapparatuses (BS#2011, BS#2021, BS#2031, BS#2041, BS#2051, BS#2061,BS#2071 and BS#2081) are arranged in accordance with a geographicalfeature. Each of indication-and-operation switches is a control switchhaving a display function. In an upper part of anindication-and-operation switch, information of whether the MRC settingrequest is made or not (evaluation state) that is reported from a basestation apparatus corresponding to the indication-and-operation switchis shown. In a lower part of the indication-and-operation switch, acurrent state (setting state) of a signal combining of the base stationapparatus is shown. “M” and “S” indicated in the upper part and lowerpart represent the maximum ratio combining (MRC) and the selectioncombining (SC), respectively.

FIG. 33 is a figure illustrating an operation method of anindication-and-operation switch provided in a console panel in the firstexample. An indication of the indication-and-operation switch (BS#2041)shown on the left side in FIG. 33 represents that an original state isthe state in which the MRC setting request from a corresponding basestation apparatus is made and an actual state is the state in which theselection combining (SC) is selected for the base station apparatus.

In the original state, suppose that an operator wants to change a signalcombining for a base station apparatus to the maximum ratio combining(MRC). In this case, when an operator operates a lower part switch, anindicator of the lower part switch indicates “M” as shown on the centerpart in FIG. 33 and then when a signal combining is changed to a maximumratio combining, an indication of the indication-and-operation switchbecomes as shown on the right side in FIG. 33.

Here, a general structure such as a push button or a touch panel can beused as an operation mechanism of an indication-and-operation switchmentioned above. For example, a liquid crystal display panel or the likecan be used for a display mechanism of an indication-and-operationswitch. A state during state transition can be expressed with variousexpression methods such as a change in a display color or a flashing.

In the console panel 10101 which realizes such operation, an evaluationstate (whether an MRC setting request is made or not) and a settingstate of each of base station apparatuses is managed by a managementtable as shown in FIG. 34.

FIG. 34 is a figure illustrating a management table used for amanagement of an evaluation state and a setting state of a plurality ofbase station apparatuses which are management targets. That is,information about an apparatus number, an evaluation state, a settingstate and a reservation mode with respect to each of base stationapparatuses are registered in a management table shown in FIG. 34. Inthe example, a management table is managed by the operation system10100.

For example, an evaluation state (evaluation status) about a basestation apparatus BS#2011 represents a state in which the MRC settingrequest (MRC is appropriate) is made. A setting state is the SC. Thestate is represented as “BS#2011MS”. In the case, a state of each ofbase station apparatuses shown in FIG. 34 can be represented withBS#2011MS, BS#2021MM, BS#2031SS, BS#2041MS, BS#2051MM, BS#2061MM,BS#2071MS and BS#2081SS.

When there is a difference between information in an evaluation statecolumn and information in a setting state column, its difference isrecognized in an apparatus and also an operator performs a changeoperation of a signal combining. In that time, a management flag is usedfor managing a state until a change operation is completed that is shownin a reservation mode column of a management table shown in FIG. 34.That is, in a management table shown in FIG. 34, information in areservation mode column is “M” with respect to a base station apparatuswhose state is BS#2041MS. This state means a state shown in a centerpart of FIG. 33 mentioned above and it represents that signal combiningis being changed. For this reason, a management flag “M” in areservation mode column of a management table is reset in a state (thatis, a state shown on the right side of FIG. 33) in which a changeoperation has been completed.

According to the first example in which such processing is performed, anoperator can adequately change a state of a signal combining for each ofbase station apparatuses while visually grasping a geographical locationof the each of base station apparatuses. A more adequate communicationstate can be realized by considering (expecting) for example, variousexternal factors mentioned above (surrounding circumstances such aswhether or not an event will be held, difference in the time or the dayof the week etc.) by an operator in advance when a change is performed.

A Second Example A Method in which a Change is Performed by a CentralApparatus

FIG. 35 is a system block diagram of an exemplary mobile communicationssystem in a second example. Further, in FIG. 35, a line representing acommunication line which connects each of base station apparatuses 2011,2021, 2031, 2041 and 2051 with each other is omitted like the case shownin FIG. 6 mentioned above.

In this example, each of base station apparatuses and the centralapparatus (monitor apparatus) 10201 are connected with each other via acontrol line (the control line 10005 shown in FIG. 25) that is not shownin FIG. 35. The central apparatus 10201 includes a CPU 10202 and astorage medium 10203 such as a memory. The CPU 10202 performs a processof a flowchart shown in FIG. 38 mentioned below, by referring to thestorage medium 10203 appropriately.

FIG. 36 is a figure showing a flow of information transmitted andreceived between a central apparatus and a base station apparatus in asequential change method according to the second example. In thisexample, the central apparatus 10201 can read out information of whetheror not the MRC setting request is made, from each of base stationapparatuses via a control line. The central apparatus 10201 can carryout a setting and release of the MRC connection mode to each of basestation apparatuses via a control line in order one by one. Hereinafter,this change procedure is described “sequential change method”.

That is, in FIG. 36, it is assumed that the central apparatus 10201 isconnected to a base station apparatus BS#1 and a base station apparatusBS#2 for convenience of explanation. In this case, first, the centralapparatus 10201 requests the base station antenna apparatus BS#1 to readout information of whether or not the MRC setting request is made. Inresponse to the request, the base station antenna apparatus BS#1transmits a processing result (MRC setting request/release request)obtained by a change request process (FIGS. 27 to 29) to the centralapparatus 10201 with a function of the MRC report module 10013 mentionedabove. In an example shown in FIG. 36, the central apparatus 10201instructs the base station antenna apparatus BS#1 to perform anoperation of the maximum ratio combining (MRC) according to a result ofa change control process (FIG. 38) described below. Next, the centralapparatus 10201 performs the same procedure as mentioned above for thebase station antenna apparatus BS#2. As a result, the central apparatus10201 instructs the base station antenna apparatus BS#2 to release anoperation of the maximum ratio combining (MRC) (that is, to start anoperation of the selection combining (SC)).

FIG. 37 is a figure illustrating a management table used for amanagement of an evaluation state and a setting state of a plurality ofbase station apparatuses which are management targets. A composition andan operation of a management table shown in FIG. 37 are equal to theseof a management table (FIG. 34) in the first example.

In this example, the management table is managed in the storage medium10203 of the central apparatus 10201 under a control of the CPU 10202.The central apparatus 10201 learns a state of the each base stationapparatus and performs a change control of a connection mode by using amanagement table (FIG. 37).

FIG. 38 shows a flowchart of a change control process by a sequentialchange method that is performed by a central apparatus in the secondexample. The flowchart shows a processing procedure performed by the CPU10202.

In step S51, the CPU 10202 judges whether or not a series of changecontrol process described below have been completed for all the basestation apparatuses. When a result of judgment in step S51 is “NO”, theCPU 10202 obtains information of whether or not an MRC setting requestis made, from a base station apparatus that is a next read-out target(step S52).

In step S53, the CPU 10202 determines whether or not a differencebetween information in an evaluation state column and information in asetting state column exists with respect to a base station apparatusthat is a processing target by referring to a management table (FIG.37).

Judging that the difference exists in step S53, the CPU 10202 instructsa base station apparatus that is a target of processing to perform asetting of the selection combining (SC) mode or the maximum ratiocombining (MRC) mode (step S54, step S55).

That is, when information in an evaluation state column is “M” andinformation in a setting state column is “S” in a management table (FIG.37), the CPU 10202 instructs a base station apparatus that is a targetof processing to perform the maximum ratio combining (MRC) mode in stepS55. On the other hand, when information in an evaluation state columnis “S” and information in a setting state column is “M” in themanagement table (FIG. 37), the CPU 10202 instructs a base stationapparatus that is a target of processing to perform a setting of aselection combining (SC) mode in step S54.

The CPU 10202 performs a series of processing mentioned above one by oneuntil judging in step S51 that the processing has been completed for allthe base station apparatuses.

Here, with reference to a management table (FIG. 37), an operationpresented by a flowchart mentioned above is described. For example, withrespect to information about the base station apparatus 2041, a state isas follows.

Information in “Evaluation state” column that is collected from the basestation apparatus 2041 is “S” that represents a release request of anMRC setting;

Information in “setting state” column which is an actual setting stateof the base station apparatus 2041 is “M” which is a maximum ratiocombining; and

Information in “reservation mode” column about the base stationapparatus 2041 is “S” which is the selection combining. That is, thecentral apparatus 10201 is just changing a mode of the base stationapparatus 2041 to the selection combining (SC) mode.

In contrast, a management table (FIG. 37) represents that the centralapparatus 10201 does not instructs other base station apparatuses otherthan the base station apparatus 2041 to perform a mode change althoughthere is a difference between information in an “evaluation state”column and information in a “setting state” column. That is, it is knownfrom the management table (FIG. 37) that a control target of the centralapparatus 10201 (CPU 10202) is the base station apparatus 2041 and otherbase station apparatuses are not a control target at present.Accordingly, according to an operation shown in a flowchart mentionedabove, in the case that for example, a next control target is the basestation apparatus 2051, the central apparatus 10201 (CPU 10202) knowsthat information in an “evaluation state” column is a “M” andinformation in a “setting state” column is a “S”. For this reason, thecentral apparatus 10201 (CPU 10202) changes an operation mode of thebase station apparatus 2051 to the MRC connection mode by setting a“reservation mode” column to “M”.

In change control processing (FIG. 37 and FIG. 38) described above, asequential change method is used in which the central apparatus 10201instructs a plurality of base station apparatuses that are managed bythe central apparatus to perform a setting in order. This method is usedfor a case in which no problem occurs on a transmission band even whenmany base station apparatuses operate in the MRC connection mode thatneeds a wide transmission band or for a case a connection mode can bechanged by spending relatively much time.

In contrast, a method described below with reference to FIG. 39 and FIG.40 can be used for a case in which a problem occurs on a transmissionband when many base station apparatuses operate in the MRC connectionmode. For this reason, in a system (batch change method) describedbelow, the central apparatus 10201 detects a state of all base stationapparatuses that are managed by the central apparatus 10201 alltogether. When a detected state is different from a previous state forall base station apparatuses, the central apparatus 10201 analyzeswhether or not a setting change of a connection mode is required andperforms a setting change to only base station apparatus to which asetting change is needed, based on a result of the analysis. Otherwise,the central apparatus 10201 determines an order of priority based on aresult of the analysis and performs a setting of a connection mode basedon the order of priority.

Here, the order of priority may be determined by analyzing an effectobtained by a setting of the MRC connection mode. Specifically, as anexample, first, an evaluation value mentioned above is calculated forall base station apparatuses which have reported the MRC setting requestby referring to FIG. 26. An order of a setting change is rearrangedaccording to a magnitude of all the calculated evaluation values withrespect to all base station apparatuses that have reported the MRCsetting request. By carrying out such processing, the MRC connectionmode can be accurately set by effectively using a limited transmissionband.

FIG. 39 is a figure showing a flow of information transmitted andreceived between a central apparatus and a base station apparatus in abatch change method according to the second example. Here, this changeprocedure is described “batch change method” compared with “sequentialchange method” mentioned above.

In an example shown in FIG. 39, it is assumed that the central apparatus10201 is connected to the base station apparatus BS#1 and the basestation apparatus BS#2 like the case shown in FIG. 36 for convenience ofexplanation. However, in this case, a batch change method is used. Forthis reason, the central apparatus 10201 requests the base stationantenna apparatus BS#1 and the base station antenna apparatus BS#2 toread out information of whether or not the MRC setting request is made.In response to this request, the base station antenna apparatus BS#1 andthe base station antenna apparatus BS#2 transmit a processing result(MRC setting request/release request) obtained by change requestprocessing (FIGS. 27 to 29) to the central apparatus 10201 with afunction of the MRC report module 10013 mentioned above. In an exampleshown in FIG. 39, the central apparatus 10201 instructs the base stationantenna apparatus BS#1 to perform an operation by the maximum ratiocombining (MRC) according to a result of change control processing (FIG.40) described below. On the other hand, the central apparatus 10201instructs the base station antenna apparatus BS#1 to release anoperation of the maximum ratio combining (MRC) (that is, to start anoperation of the selection combining (SC)). In this case, theinstructions to two base station apparatuses are performed together.

FIG. 40 is a flowchart of change control processing using a batch changemethod performed by a central apparatus in the second example. Theflowchart shows a processing procedure that is performed by the CPU10202.

In step S61, the CPU 10202 judges whether or not a processing forobtaining information on the MRC setting request from all the basestation apparatuses subject to the CPU 10202 is completed. When a resultof judgment in step S61 is “NO”, the CPU 10202 obtains information ofwhether or not the MRC setting request is made, from all the basestation apparatuses subject to the CPU 10202 (step S62).

When it is confirmed in step S61 that an information acquisition fromthe all base station apparatuses has been completed (in case of YESjudgment), the CPU 10202 analyzes a priority mentioned above based onthe obtained information (step S63).

Next, the CPU 10202 determines an order of priority of a changeoperation and whether or not a change is required based on a result ofthe analysis in step S63 (step S64).

In step S65, the CPU 10202 judges whether or not change controlprocessing to all the base station apparatuses has been completed. Whena result of judgment in step S65 is “NO”, the CPU 10202 judges whetheror not the next noted base station apparatus is a base station apparatusthat is a change target among all the base station apparatuses byreferring to a processing result obtained in step S64 (Step S66)

Judging in step S66 that the next noted base station apparatus is a basestation apparatus that is a change target, the CPU 10202 determineswhether or not a difference between information in an evaluation statecolumn and information in a setting state column exists with respect toa base station apparatus that is a target of processing by referring tothe management table (FIG. 37).

Judging that a difference exists by a judgment in step S67, the CPU10202 instructs a base station apparatus that is a target of processingto perform a setting of the selection combining (SC) mode or the maximumratio combining (MRC) mode (step S68, step S69). This setting processingitself is equal to that of a sequential change method (FIG. 38)mentioned above.

In an example mentioned above with reference to FIGS. 35 to 40, forconvenience of explanation, a change procedure of the MRC connectionmode is described for a local area. Accordingly, here, a case in which aconnection mode is changed in a wide area will be described withreference to FIG. 41.

FIG. 41 is a figure illustrating a management table used for amanagement of an evaluation state and a setting state of a plurality ofbase station apparatuses which are management targets. A composition andan operation of a management table shown in FIG. 41 are equal to that ofa management table (FIG. 34) in the first example. The management tableis managed in the storage medium 10203 of the central apparatus 10201under a control of the CPU 10202. The central apparatus 10201 learns astate of the each base station apparatus and performs a change controlof a connection mode by using the management table (FIG. 41).

That is, an example shown in FIG. 41 assumes the state that is similarto a distribution state of mobile terminals in an actual service areaand corresponds to an operation control state of fifteen base stationapparatuses exemplified in FIG. 23 and FIG. 24 described above. Themanagement table shown in FIG. 41 represents management information whenrealizing the operation control state shown in FIG. 24 from theoperation control state shown in FIG. 23.

That is, in a “setting state” column shown in the management table (FIG.41), actual operation states of the fifteen base station apparatuses ata time t1 is listed in FIG. 23. More specifically, with respect to thebase station apparatuses (BS#2021, BS#2031, BS#2041, BS#2051, BS#2061,BS#2081 and BS#2091) which are selecting an MRC as shown in FIG. 23,information in a “setting state” column in the management table (FIG.41) is “M” that means an MRC mode.

In contrast, base station apparatuses which are selecting an MRC at atime t2 are BS#2071, BS#2081, BS#2101, BS#2111, BS#2131 and BS#2141 asshown in FIG. 24.

Accordingly, the central apparatus 10201 is needed to perform a changeof a plurality of base station apparatuses in a period from the time t1to the time t2.

More specifically, in order to realize the operation control state shownin FIG. 24, first, for example, at the time t1, the fifteen base stationapparatuses judge whether or not the MRC setting request is required bya change request process (FIGS. 27 to 29) mentioned above. The centralapparatus 10201 can collect a judgment result of whether or not the MRCsetting request is required from the fifteen base station apparatuses bya procedure mentioned above with reference to FIG. 36 and FIG. 39. Thecollected result is registered in an “evaluation state” column shown inFIG. 41.

Accordingly, in this case, it is necessary to change an operationsetting of a target base station apparatus according to information in a“setting state” column and information in an “evaluation state” columnof the management table (FIG. 41). That is, if there is a differencebetween information in a “setting state” column and information in an“evaluation state” column in the management table (FIG. 41) with respectto a base station apparatus, an operation setting of the base stationapparatus has to be changed.

As mentioned above in a description of a management table shown in FIG.34, a “reservation mode” is a column for a management flag thatrepresents a difference between information in a “setting state” columnand information in “the evaluation state” column. Therefore, in FIG. 41,for example, with respect to the base station apparatus 2011, becauseinformation in a “setting state” column is equal to information in an“evaluation state” column, information in a “reservation mode” column isreset to “-”. In contrast, for example, with respect to the base stationapparatus 2021, information in a “setting state” column is “M”indicating a maximum ratio combining. However, information in an“evaluation state” column is “S” indicating the selection combining. Forthis reason, since a mode of the base station apparatus 2021 has to bechanged to the selection combining mode, therefore, a “reservation mode”column is set to “S”. That is, in the management table shown in FIG. 41,the central apparatus 10201 has to perform a change request process ofan operation setting with respect to a base station apparatus of whichinformation set in a “reservation mode” column is “S” or “M” within atime between t1 and t2. As a result, at the time t2, a distributionstate shown in FIG. 24 can be realized with respect to base stationapparatuses (BS#2071, BS#2081, BS#2101, BS#2111, BS#2131 and BS#2141)which are selecting an MRC mode.

A Third Example A Method of Which a Change is Performed by a BaseStation Apparatus Itself

Next, a method of which a change of a connection mode is performed by abase station apparatus itself will be described.

FIG. 42 is a figure illustrating a management table that is self-managedby a base station apparatus in a third example. In this example, thebase station apparatus 10000 described with reference to FIG. 25 has amanagement table outlined in FIG. 42 in the storage medium 10004. Acomposition and an operation of the management table (FIG. 42) are equalto these of management table (FIG. 34) mentioned above with theexception that a target base station apparatus is only an own basestation apparatus.

That is, in this example, the base station apparatus 10000 (CPU 10003)performs a change request process mentioned above (FIGS. 27 to 29). Byreferring to the management table (FIG. 42) stored in the storage medium10004, the base station apparatus 10000 manages an own evaluation state.The base station apparatus 10000 itself changes own operation settingaccording to information in a “setting state” column and information inan “evaluation state” column in the management table (FIG. 42).

FIG. 43 is a figure illustrating a configuration of a mobilecommunications system in the third example. In this example, the basestation apparatuses 2011, 2021 and 2031 (BS#1, BS#2, and BS#3) areconnected to the high speed line 1001 and the low speed line 1002mentioned above. In this example, the high speed line 1001 is used forthe MRC connection mode. The low speed line 1002 is used for the SCconnection mode. The base station apparatuses are connected with a lineconnection controller 10300 via a control line which corresponds to thecontrol line 10005 shown in FIG. 25.

When a base station apparatus that is managed by a line connectioncontroller 10300 determines that a change of a connection mode isnecessary (that is, in case of that a setting of a reservation mode isperformed), the line connection controller 10300 instructs the basestation apparatus to perform the setting change. Each base stationapparatus requests the line connection controller 10300 to perform anestablishment of a connection mode with the high speed line 1001 and thelow speed line 1002 or a change of an established connection mode.

FIG. 44 is a figure showing a flow of information transmitted andreceived between a line connection controller and a base stationapparatus in the third example.

In FIG. 44, the base station apparatuses BS#1, BS#2 and BS#3 calculatean evaluation value in a coverage area of their own apparatus bythemselves, respectively and also determine whether or not a change of aconnection mode is necessary (whether an MRC setting is needed or not).Each of base station apparatuses stores the evaluation value and thedetermination result in a management table (FIG. 42) in the storagemedium 10004.

When information in a “setting state” column and information in an“evaluation state” column in a management table are not identical, forexample, the base station apparatus (BS#1) transmits a change request ofa connection mode to the line connection controller 10300.

In response to a receipt of a change request, the line connectioncontroller 10300 judges whether or not a communication line to be usedby the base station apparatus is available. Moreover, the lineconnection controller 10300 confirms that a capacity of a communicationline to be used does not reach a limit. The line connection controller10300 performs processing corresponding to a content requested from thebase station apparatus (BS#1) based on these results of judgment andalso transmits a processing result to the base station apparatus.

In the example, a series of operations mentioned above are performed ineach of the base station apparatuses. As a result, each of the basestation apparatuses can change a connection mode by itself.

Thus, according to the exemplary embodiment mentioned above and themobile communications system according to its example, when a wirelesssignal transmitted from one mobile terminal is received by a pluralityof base station apparatuses, information corresponding to the wirelesssignal can be accurately combined by selecting a most suitable combiningpoint, that is a maximum ratio combining point or a selection combiningpoint, according to an external factors and/or a change of adistribution state of a mobile terminal under communication that existsin a service area covered by a base station apparatus with which themobile terminal communicates.

Accordingly, because a reception gain of a signal that is sent to a basestation apparatus from a mobile terminal is improved, as a result, atransmission power from a mobile terminal can be reduced. That is,according to the exemplary embodiment, an increase of a capacity of aline can be realized.

According to the exemplary embodiment, a connection relationship inwhich a plurality of base station apparatuses, the maximum ratiocombining point (MRC-P) and the selection combining (SC-P) are connectedwith each other via the high speed line 1001 can be dynamically changed.Therefore, a number of definition for network-related apparatuses whichchanges according to a regional traffic condition or an existencecondition of an obstacle to a radio wave (for example, a structure, along time stop of a vehicle or the like) can be reduced.

While the invention has been particularly shown and described withreference to exemplary embodiments thereof, the invention is not limitedto these exemplary embodiments. It will be understood by those ofordinary skill in the art that various changes in form and details maybe made therein without departing from the spirit and scope of thepresent invention as defined by the claims.

Further, it is the inventor's intention to retain all equivalents of theclaimed invention even if the claims are amended during prosecution.

1. A mobile communications system, comprising: a plurality of basestation apparatuses which are located at geographically dispersedlocations and perform a wireless communication with a mobile device; amaximum ratio combining unit which is connectable with said plurality ofbase station apparatuses for a communication via a first communicationline and performs maximum ratio combining processing based oninformation corresponding to a received signal from said mobile device,said information being transmitted from said plurality of base stationapparatuses; a selection combining unit which is connectable with saidplurality of base station apparatuses for a communication via a secondcommunication line and performs selection combining processing based oninformation corresponding to a received signal from said mobile device,said information being transmitted from said plurality of base stationapparatuses; and a selection unit which selects one or both of saidmaximum ratio combining unit and said selection combining unit accordingto at least one of an external factor and a change of a distributionstate of a mobile device under communication that exists in a coveragearea of said plurality of base station apparatuses with which saidmobile device performs a wireless communication, when signal combiningis performed based on said information corresponding to said receivedsignal from said mobile device, said information being transmitted fromsaid plurality of base station apparatuses, in response to reception ofa wireless signal by said plurality of base station apparatuses, saidwireless signal being transmitted from one mobile device.
 2. The mobilecommunications system according to claim 1, wherein said plurality ofbase station apparatuses request said selection unit to change adestination of said information corresponding to said received signalfrom said mobile device to either said maximum ratio combining unit orsaid selection combining unit according to said change of saiddistribution state of said mobile device under communication.
 3. Themobile communications system according to claim 2, wherein saidplurality of base station apparatuses determine said change of saiddistribution state of said mobile device under communication based on anamount of electric power of an up link in a wireless section betweensaid mobile device and said plurality of base station apparatuses. 4.The mobile communications system according to claim 2, wherein saidplurality of base station apparatuses determine said change of saiddistribution state of said mobile device under communication based on arate about an up link in said plurality of base station apparatuses. 5.The mobile communications system according to claim 2, wherein saidplurality of base station apparatuses determine said change of saiddistribution state of said mobile device under communication based onthe number of said mobile devices under communication that exist in saidcoverage area of said plurality of base station apparatuses.
 6. Themobile communications system according to claim 2, wherein whentransmitting said information corresponding to said received signal fromsaid mobile device, said plurality of base station apparatuses transmitsaid information either in a form for a transmission to said maximumratio combining unit or in a form for a transmission to said selectioncombining unit.
 7. The mobile communications system according to claim2, wherein when transmitting said information corresponding to saidreceived signal from said mobile device, said plurality of base stationapparatuses can dynamically switch between a form for a transmission tosaid maximum ratio combining unit and a form for a transmission to saidselection combining unit.
 8. The mobile communications system accordingto claim 7, wherein when said plurality of base station apparatuseschanges said form for a transmission to said selection combining unitinto said form for a transmission to said maximum ratio combining unitupon transmitting said information corresponding to said received signalfrom said mobile device, said plurality of base station apparatusescontinues to transmit said information to said selection combining unitvia said second communication line, starts to transmit said informationto said maximum ratio combining unit via said first communication lineand stops transmitting said information to said selection combining unitwhen said maximum ratio combining unit can perform said maximum ratiocombining processing to said information.
 9. The mobile communicationssystem according to claim 7, wherein when said plurality of base stationapparatuses changes said form for a transmission to said maximum ratiocombining unit into said form for a transmission to said selectioncombining unit upon transmitting said information corresponding to saidreceived signal from said mobile device, said plurality of base stationapparatuses continues to transmit said information to said maximum ratiocombining unit via said first communication line, starts to transmitsaid information to said selection combining unit via said secondcommunication line and stops transmitting said information to saidmaximum ratio combining unit when said selection combining unit canperform said selection combining processing to said information.
 10. Themobile communications system according to claim 2, wherein saidselection unit including: a man-machine interface by which an operatorcan select whether or not to perform a change according to a changerequest from said plurality of base station apparatuses; and a basestation apparatus control apparatus which selects at least one of saidmaximum ratio combining unit and said selection combining unit byconsidering a result of change by said man-machine interface.
 11. Themobile communications system according to claim 2, wherein saidselection unit including: an external apparatus which judges whether ornot to perform a change according to a change request from saidplurality of base station apparatuses; and a base station apparatuscontrol apparatus which selects at least one of said maximum ratiocombining unit and said selection combining unit by considering a resultof a change judgment by said external apparatus.
 12. The mobilecommunications system according to claim 11, wherein when judgingwhether or not to perform said change, said external apparatus judges atleast one of whether or not said change is required and an order ofpriority of said change with respect to said plurality of base stationapparatuses according to said external factor or an evaluation valueabout said distribution state of said mobile device under communication.13. The mobile communications system according to claim 2, wherein saidselection unit including: said plurality of base station apparatuseswhich judge whether or not said change request is made and also judgewhether or not to perform said change according to a result of saidjudgment therein; and a base station apparatus control apparatus whichselects at least one of said maximum ratio combining unit and saidselection combining unit by considering a result of said change judgmentby said plurality of base station apparatuses.
 14. The mobilecommunications system according to claim 1, wherein a communication rateof said first communication line is at least equal to a communicationrate of a code information transmitted in a wireless section betweensaid mobile terminal and said plurality of base station apparatus. 15.The mobile communications system according to claim 1, wherein saidexternal factor is at least one of a difference in a time zone, adifference in a days of the week and whether an event is held or not.16. A base station apparatus which performs a wireless communicationwith a mobile device, comprising: a communication control module whichtransmits information by establishing a communication link with at leastone of a first communication line used for a communication with amaximum ratio combining unit that performs maximum ratio combiningprocessing and a second communication line used for a communication witha selection combining unit that performs selection combining processingbased on information corresponding to a received signal from said mobiledevice; and a request module which requests an external apparatus tochange a destination of said information corresponding to said receivedsignal from said mobile device to either said maximum ratio combiningunit or said selection combining unit according to a change of adistribution state of said mobile device under communication.
 17. Thebase station apparatus according to claim 16, wherein said change ofsaid distribution state of said mobile device under communication isdetermined based on an amount of electric power of an up link in awireless section between said mobile terminal and said base stationapparatus.
 18. The base station apparatus according to claim 16, whereinsaid change of said distribution state of said mobile device undercommunication is determined based on a rate about an up link in saidbase station apparatus.
 19. The base station apparatus according toclaim 16, wherein said change of said distribution state of said mobiledevice under communication is determined based on the number of mobiledevices under communication that exist in a coverage area of said basestation apparatus.
 20. The base station apparatus according to claim 16,wherein when transmitting said information corresponding to saidreceived signal from said mobile device, said information is transmittedeither in a form for a transmission to said maximum ratio combining unitor in a form for a transmission to said selection combining unit. 21.The base station apparatus according to claim 16, wherein whentransmitting said information corresponding to said received signal fromsaid mobile device, a form for a transmission to said maximum ratiocombining unit and a form for a transmission to said selection combiningunit can be dynamically switched.
 22. The base station apparatusaccording to claim 21, wherein when said base station apparatus changessaid form for a transmission to said selection combining unit into saidform for a transmission to said maximum ratio combining unit upontransmitting said information corresponding to said received signal fromsaid mobile device, said base station apparatus continues to transmitsaid information to said selection combining unit via said secondcommunication line, starts to transmit said information to said maximumratio combining unit via said first communication line and stopstransmitting said information to said selection combining unit when saidmaximum ratio combining unit can perform said maximum ratio combiningprocessing to said information.
 23. The base station apparatus accordingto claim 21, wherein when said base station apparatus changes said formfor a transmission to said maximum ratio combining unit into said formfor a transmission to said selection combining unit upon transmittingsaid information corresponding to said received signal from said mobiledevice, said base station apparatus continues to transmit saidinformation to said maximum ratio combining unit via said firstcommunication line, starts to transmit said information to saidselection combining unit via said second communication line and stopstransmitting said information to said maximum ratio combining unit whensaid selection combining unit can perform said selection combiningprocessing to said information.
 24. The base station apparatus accordingto claim 16, wherein a communication rate of said first communicationline is at least equal to a communication rate of a code informationtransmitted in a wireless section between said mobile terminal and saidbase station apparatus.
 25. A mobile communications system, comprising:a plurality of base station apparatuses which are located atgeographically dispersed locations and perform a wireless communicationwith a mobile device; a maximum ratio combining means which isconnectable with said plurality of base station apparatuses for acommunication via a first communication line and performs maximum ratiocombining processing based on information corresponding to a receivedsignal from said mobile device, said information being transmitted fromsaid plurality of base station apparatuses; a selection combining meanswhich is connectable with said plurality of base station apparatuses fora communication via a second communication line and performs selectioncombining processing based on information corresponding to a receivedsignal from said mobile device, said information being transmitted fromsaid plurality of base station apparatuses; and a selection means whichselects one or both of said maximum ratio combining means and saidselection combining means according to at least one of an externalfactor and a change of a distribution state of a mobile device undercommunication that exists in a coverage area of said plurality of basestation apparatuses with which said mobile device performs a wirelesscommunication, when signal combining is performed based on saidinformation corresponding to said received signal from said mobiledevice, said information being transmitted from said plurality of basestation apparatuses, in response to reception of a wireless signal bysaid plurality of base station apparatuses, said wireless signal beingtransmitted from one mobile device.
 26. A base station apparatus whichperforms a wireless communication with a mobile device, comprising: acommunication control means which transmits information by establishinga communication link with at least one of a first communication lineused for a communication with a maximum ratio combining means thatperforms maximum ratio combining processing and a second communicationline used for a communication with a selection combining means thatperforms selection combining processing based on informationcorresponding to a received signal from said mobile device; and arequest means which requests an external apparatus to change adestination of said information corresponding to said received signalfrom said mobile device to either said maximum ratio combining means orsaid selection combining means according to a change of a distributionstate of said mobile device under communication.
 27. A control method ofa mobile communications system, comprising: connecting a plurality ofbase station apparatuses which are located at geographically dispersedlocations and perform a wireless communication with a mobile device witha maximum ratio combining unit that performs maximum ratio combiningprocessing via a first communication line based on informationcorresponding to a received signal from said mobile device, saidinformation being transmitted from said plurality of base stationapparatuses, and also connecting said plurality of base stationapparatuses with a selection combining unit that performs selectioncombining processing based on said information via a secondcommunication line; and selecting at least one of said maximum ratiocombining unit or said selection combining unit according to at leastone of an external factor or a change of a distribution state of saidmobile device under communication that exists in a coverage area of saidplurality of base station apparatuses with which said mobile deviceperforms a wireless communication when performing signal combining basedon said information corresponding to said received signal from saidmobile device, said information being transmitted from said plurality ofbase station apparatuses in response to a reception of a wireless signaltransmitted from one mobile device in said plurality of base stationapparatuses.
 28. The control method according to claim 27, wherein aline in which a communication can be performed at a communication ratethat is at least equal to a communication rate of a code informationtransmitted in a wireless section between said mobile terminal and saidplurality of base station apparatuses is used for said firstcommunication line.
 29. A computer program for controlling an operationof a base station apparatus which performs a wireless communication witha mobile device, said computer program realizing functions of asfollows: a communication control function which transmits information byestablishing a communication link with at least one of a firstcommunication line used for a communication with a maximum ratiocombining unit that performs maximum ratio combining processing and asecond communication line used for a communication with a selectioncombining unit that performs selection combining processing based oninformation corresponding to a received signal from said mobile device;and a request function which requests an external apparatus to change adestination of said information corresponding to said received signalfrom said mobile device to either said maximum ratio combining unit orsaid selection combining unit according to a change of a distributionstate of said mobile device under communication.